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contrib/postgres_fdw/expected/query_cancel.out
34 строки
2 KB
Tom Lane
postgres_fdw: re-issue cancel requests a few times if necessary.
23 дек 2024, 23:14
23 дек 2024, 23:14
c431986
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SELECT version() ~ 'cygwin' AS skip_test \gset \if :skip_test \quit \endif -- Let's test canceling a remote query. Use a table that does not have -- remote_estimate enabled, else there will be multiple queries to the -- remote and we might unluckily send the cancel in between two of them. -- First let's confirm that the query is actually pushed down. EXPLAIN (VERBOSE, COSTS OFF) SELECT count(*) FROM ft1 a CROSS JOIN ft1 b CROSS JOIN ft1 c CROSS JOIN ft1 d; QUERY PLAN --------------------------------------------------------------------------------------------------------------------------------------------------------------------- Foreign Scan Output: (count(*)) Relations: Aggregate on ((((public.ft1 a) INNER JOIN (public.ft1 b)) INNER JOIN (public.ft1 c)) INNER JOIN (public.ft1 d)) Remote SQL: SELECT count(*) FROM ((("S 1"."T 1" r1 INNER JOIN "S 1"."T 1" r2 ON (TRUE)) INNER JOIN "S 1"."T 1" r4 ON (TRUE)) INNER JOIN "S 1"."T 1" r6 ON (TRUE)) (4 rows) BEGIN; -- Make sure that connection is open and set up. SELECT count(*) FROM ft1 a; count ------- 822 (1 row) -- On most machines, 10ms will be enough to be sure that we've sent the slow -- query. We may sometimes exercise the race condition where we send cancel -- before the remote side starts the query, but that's fine too. SET LOCAL statement_timeout = '10ms'; -- This would take very long if not canceled: SELECT count(*) FROM ft1 a CROSS JOIN ft1 b CROSS JOIN ft1 c CROSS JOIN ft1 d; ERROR: canceling statement due to statement timeout COMMIT;