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Prevent asynchronous execution of direct foreign-table modifications.

author Etsuro Fujita <efujita@postgresql.org>

2021年5月13日 11:00:00 +0000 (20:00 +0900)

committer Etsuro Fujita <efujita@postgresql.org>

2021年5月13日 11:00:00 +0000 (20:00 +0900)

Commits 27e1f1456 and 86dc90056, which were independently discussed,
cause a crash when executing an inherited foreign UPDATE/DELETE query
with asynchronous execution enabled, where children of an Append node
that is the direct/indirect child of the ModifyTable node are rewritten
so as to modify foreign tables directly by postgresPlanDirectModify();
as in that case the direct modifications are executed asynchronously,
which is not currently supported by asynchronous execution. Fix by
disabling asynchronous execution of the direct modifications in that
function.

Author: Etsuro Fujita
Reviewed-by: Amit Langote
Discussion: https://postgr.es/m/CAPmGK158e9sJOfuWxfn%2B0ynrspXQU3JhNjSCbaoeSzMvnga%2Bbw%40mail.gmail.com

contrib/postgres_fdw/expected/postgres_fdw.out patch | blob | blame | history

contrib/postgres_fdw/postgres_fdw.c patch | blob | blame | history

contrib/postgres_fdw/sql/postgres_fdw.sql patch | blob | blame | history

diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out

index 0b0c45f0d9a189b5759991a52716c0097ed30fca..7df30010f25e9e3ab8677c19400558f406c80d76 100644 (file)

--- a/contrib/postgres_fdw/expected/postgres_fdw.out

+++ b/contrib/postgres_fdw/expected/postgres_fdw.out

@@ -10154,6 +10154,61 @@ DROP TABLE base_tbl3;

DROP TABLE base_tbl4;

RESET enable_mergejoin;

RESET enable_hashjoin;

+-- Test that UPDATE/DELETE with inherited target works with async_capable enabled

+EXPLAIN (VERBOSE, COSTS OFF)

+UPDATE async_pt SET c = c || c WHERE b = 0 RETURNING *;

+ QUERY PLAN

+----------------------------------------------------------------------------------------------------------

+ Update on public.async_pt

+ Output: async_pt_1.a, async_pt_1.b, async_pt_1.c

+ Foreign Update on public.async_p1 async_pt_1

+ Foreign Update on public.async_p2 async_pt_2

+ Update on public.async_p3 async_pt_3

+ -> Append

+ -> Foreign Update on public.async_p1 async_pt_1

+ Remote SQL: UPDATE public.base_tbl1 SET c = (c || c) WHERE ((b = 0)) RETURNING a, b, c

+ -> Foreign Update on public.async_p2 async_pt_2

+ Remote SQL: UPDATE public.base_tbl2 SET c = (c || c) WHERE ((b = 0)) RETURNING a, b, c

+ -> Seq Scan on public.async_p3 async_pt_3

+ Output: (async_pt_3.c || async_pt_3.c), async_pt_3.tableoid, async_pt_3.ctid, NULL::record

+ Filter: (async_pt_3.b = 0)

+(13 rows)

+UPDATE async_pt SET c = c || c WHERE b = 0 RETURNING *;

+ a | b | c

+------+---+----------

+ 1000 | 0 | 00000000

+ 2000 | 0 | 00000000

+ 3000 | 0 | 00000000

+(3 rows)

+EXPLAIN (VERBOSE, COSTS OFF)

+DELETE FROM async_pt WHERE b = 0 RETURNING *;

+ QUERY PLAN

+------------------------------------------------------------------------------------------

+ Delete on public.async_pt

+ Output: async_pt_1.a, async_pt_1.b, async_pt_1.c

+ Foreign Delete on public.async_p1 async_pt_1

+ Foreign Delete on public.async_p2 async_pt_2

+ Delete on public.async_p3 async_pt_3

+ -> Append

+ -> Foreign Delete on public.async_p1 async_pt_1

+ Remote SQL: DELETE FROM public.base_tbl1 WHERE ((b = 0)) RETURNING a, b, c

+ -> Foreign Delete on public.async_p2 async_pt_2

+ Remote SQL: DELETE FROM public.base_tbl2 WHERE ((b = 0)) RETURNING a, b, c

+ -> Seq Scan on public.async_p3 async_pt_3

+ Output: async_pt_3.tableoid, async_pt_3.ctid

+ Filter: (async_pt_3.b = 0)

+(13 rows)

+DELETE FROM async_pt WHERE b = 0 RETURNING *;

+ a | b | c

+------+---+----------

+ 1000 | 0 | 00000000

+ 2000 | 0 | 00000000

+ 3000 | 0 | 00000000

+(3 rows)

-- Check EXPLAIN ANALYZE for a query that scans empty partitions asynchronously

DELETE FROM async_p1;

DELETE FROM async_p2;

diff --git a/contrib/postgres_fdw/postgres_fdw.c b/contrib/postgres_fdw/postgres_fdw.c

index cb757d940455758ac8a3dc03df140ec1fc212454..c48a421e88b2f31514a44e4f47512a3ca41f7d75 100644 (file)

--- a/contrib/postgres_fdw/postgres_fdw.c

+++ b/contrib/postgres_fdw/postgres_fdw.c

@@ -2530,6 +2530,13 @@ postgresPlanDirectModify(PlannerInfo *root,

rebuild_fdw_scan_tlist(fscan, returningList);

}

+ /*

+ * Finally, unset the async-capable flag if it is set, as we currently

+ * don't support asynchronous execution of direct modifications.

+ */

+ if (fscan->scan.plan.async_capable)

+ fscan->scan.plan.async_capable = false;

table_close(rel, NoLock);

return true;

}

diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql

index 53adfe2abc8954d04a79cbac6c184b28267e9f9d..78379bdea5bc3f45dfb64dac92df9ed642ed67e7 100644 (file)

--- a/contrib/postgres_fdw/sql/postgres_fdw.sql

+++ b/contrib/postgres_fdw/sql/postgres_fdw.sql

@@ -3237,6 +3237,14 @@ DROP TABLE base_tbl4;

RESET enable_mergejoin;

RESET enable_hashjoin;

+-- Test that UPDATE/DELETE with inherited target works with async_capable enabled

+EXPLAIN (VERBOSE, COSTS OFF)

+UPDATE async_pt SET c = c || c WHERE b = 0 RETURNING *;

+EXPLAIN (VERBOSE, COSTS OFF)

+DELETE FROM async_pt WHERE b = 0 RETURNING *;

-- Check EXPLAIN ANALYZE for a query that scans empty partitions asynchronously

DELETE FROM async_p1;

DELETE FROM async_p2;

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