From ab0925cd4069d1f98df3ff58bc563e6852adc2f6 Mon Sep 17 00:00:00 2001 From: Jelte Fennema-Nio Date: Tue, 25 Jun 2024 10:11:02 +0200 Subject: [PATCH v3 1/3] Make postgres_fdw cancel test not flaky anymore The postgres_fdw cancel test turned out to be flaky. The reason for this was that the cancel was sometimes sent earlier than intended. It was meant to be sent during the actual CROSS JOIN, but (especially on slow systems) it was sometimes sent in between two queries. This patch tries to remove that issue in two ways: 1. Reduce the amount of queries that are sent by postgres_fdw, by placing the test before enabling use_remote_estimate on any of the tables in question. 2. Increasing the statement_timeout to 100ms Reported-By: Alexander Lakhin --- .../postgres_fdw/expected/postgres_fdw.out | 35 ++++++++++--------- contrib/postgres_fdw/sql/postgres_fdw.sql | 19 +++++----- 2 files changed, 30 insertions(+), 24 deletions(-) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index ea566d5034..16071b3f7d 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -250,6 +250,25 @@ SELECT c3, c4 FROM ft1 ORDER BY c3, c1 LIMIT 1; -- should work again (1 row) \set VERBOSITY default +-- Let's test canceling a remote query, we do this before enabling +-- use_remote_estimate on ft2 to avoid sending many queries to the remote +-- server. Otherwise, we might be unlucky and the cancel to the remote might be +-- sent right inbetween two of the queries, causing a flaky test. First let's +-- confirm that the query is actually pushed down. +EXPLAIN (VERBOSE, COSTS OFF) SELECT count(*) FROM ft1 CROSS JOIN ft2 CROSS JOIN ft4 CROSS JOIN ft5; + QUERY PLAN +--------------------------------------------------------------------------------------------------------------------------------------------------------------------- + Foreign Scan + Output: (count(*)) + Relations: Aggregate on ((((public.ft1) INNER JOIN (public.ft2)) INNER JOIN (public.ft4)) INNER JOIN (public.ft5)) + Remote SQL: SELECT count(*) FROM ((("S 1"."T 1" r1 INNER JOIN "S 1"."T 1" r2 ON (TRUE)) INNER JOIN "S 1"."T 3" r4 ON (TRUE)) INNER JOIN "S 1"."T 4" r6 ON (TRUE)) +(4 rows) + +BEGIN; +SET LOCAL statement_timeout = '100ms'; +select count(*) from ft1 CROSS JOIN ft2 CROSS JOIN ft4 CROSS JOIN ft5; -- this takes very long +ERROR: canceling statement due to statement timeout +COMMIT; -- Now we should be able to run ANALYZE. -- To exercise multiple code paths, we use local stats on ft1 -- and remote-estimate mode on ft2. @@ -2760,22 +2779,6 @@ SELECT t1.c1, t2.c2 FROM v4 t1 LEFT JOIN ft5 t2 ON (t1.c1 = t2.c1) ORDER BY t1.c (10 rows) ALTER VIEW v4 OWNER TO regress_view_owner; --- Make sure this big CROSS JOIN query is pushed down -EXPLAIN (VERBOSE, COSTS OFF) SELECT count(*) FROM ft1 CROSS JOIN ft2 CROSS JOIN ft4 CROSS JOIN ft5; - QUERY PLAN ---------------------------------------------------------------------------------------------------------------------------------------------------------------------- - Foreign Scan - Output: (count(*)) - Relations: Aggregate on ((((public.ft1) INNER JOIN (public.ft2)) INNER JOIN (public.ft4)) INNER JOIN (public.ft5)) - Remote SQL: SELECT count(*) FROM ((("S 1"."T 1" r1 INNER JOIN "S 1"."T 1" r2 ON (TRUE)) INNER JOIN "S 1"."T 3" r4 ON (TRUE)) INNER JOIN "S 1"."T 4" r6 ON (TRUE)) -(4 rows) - --- Make sure query cancellation works -BEGIN; -SET LOCAL statement_timeout = '10ms'; -select count(*) from ft1 CROSS JOIN ft2 CROSS JOIN ft4 CROSS JOIN ft5; -- this takes very long -ERROR: canceling statement due to statement timeout -COMMIT; -- ==================================================================== -- Check that userid to use when querying the remote table is correctly -- propagated into foreign rels present in subqueries under an UNION ALL diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index b57f8cfda6..f9af38b44b 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -242,6 +242,17 @@ ALTER USER MAPPING FOR CURRENT_USER SERVER loopback SELECT c3, c4 FROM ft1 ORDER BY c3, c1 LIMIT 1; -- should work again \set VERBOSITY default +-- Let's test canceling a remote query, we do this before enabling +-- use_remote_estimate on ft2 to avoid sending many queries to the remote +-- server. Otherwise, we might be unlucky and the cancel to the remote might be +-- sent right inbetween two of the queries, causing a flaky test. First let's +-- confirm that the query is actually pushed down. +EXPLAIN (VERBOSE, COSTS OFF) SELECT count(*) FROM ft1 CROSS JOIN ft2 CROSS JOIN ft4 CROSS JOIN ft5; +BEGIN; +SET LOCAL statement_timeout = '100ms'; +select count(*) from ft1 CROSS JOIN ft2 CROSS JOIN ft4 CROSS JOIN ft5; -- this takes very long +COMMIT; + -- Now we should be able to run ANALYZE. -- To exercise multiple code paths, we use local stats on ft1 -- and remote-estimate mode on ft2. @@ -742,14 +753,6 @@ SELECT t1.c1, t2.c2 FROM v4 t1 LEFT JOIN ft5 t2 ON (t1.c1 = t2.c1) ORDER BY t1.c SELECT t1.c1, t2.c2 FROM v4 t1 LEFT JOIN ft5 t2 ON (t1.c1 = t2.c1) ORDER BY t1.c1, t2.c1 OFFSET 10 LIMIT 10; ALTER VIEW v4 OWNER TO regress_view_owner; --- Make sure this big CROSS JOIN query is pushed down -EXPLAIN (VERBOSE, COSTS OFF) SELECT count(*) FROM ft1 CROSS JOIN ft2 CROSS JOIN ft4 CROSS JOIN ft5; --- Make sure query cancellation works -BEGIN; -SET LOCAL statement_timeout = '10ms'; -select count(*) from ft1 CROSS JOIN ft2 CROSS JOIN ft4 CROSS JOIN ft5; -- this takes very long -COMMIT; - -- ==================================================================== -- Check that userid to use when querying the remote table is correctly -- propagated into foreign rels present in subqueries under an UNION ALL base-commit: 54508209178bc73a497c460bd0ffd1645dceb1a2 -- 2.34.1