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207391bc54
Since the parent table of a hypertable cannot contain any rows including it in the plan is not necessary. PostgreSQL might also not have good statistics for the main table as autoanalyze is triggered by inserts which never happen to the main table, leading to worse plans. This patch adds a new guc enable_constraint_exclusion to disable planner constraint exclusion. Constraint exclusion will not work with cursors and WHERE CURRENT OF so the new guc will allow you to disable that feature. This patch also fixes constraint exclusion for JOINs and sort optimization for queries with chunks_in.
44 lines
1.4 KiB
PL/PgSQL
44 lines
1.4 KiB
PL/PgSQL
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CREATE TABLE cursor_test(time timestamptz, device_id int, temp float);
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SELECT create_hypertable('cursor_test','time');
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INSERT INTO cursor_test SELECT '2000-01-01',1,0.5;
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INSERT INTO cursor_test SELECT '2001-01-01',1,0.5;
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INSERT INTO cursor_test SELECT '2002-01-01',1,0.5;
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\set ON_ERROR_STOP 0
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BEGIN;
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DECLARE c1 SCROLL CURSOR FOR SELECT * FROM cursor_test;
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FETCH NEXT FROM c1;
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-- this will produce an error because PostgreSQL checks
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-- for the existence of a scan node with the relation id for every relation
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-- used in the update plan in the plan of the cursor.
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--
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-- constraint exclusion will make this easier to hit
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-- because constraint exclusion only works for SELECT
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-- and UPDATE statements will still have parent tables in
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-- the generated plans
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UPDATE cursor_test SET temp = 0.7 WHERE CURRENT OF c1;
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COMMIT;
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-- test cursor with no chunks left after runtime exclusion
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BEGIN;
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DECLARE c1 SCROLL CURSOR FOR SELECT * FROM cursor_test WHERE time > now();
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UPDATE cursor_test SET temp = 0.7 WHERE CURRENT OF c1;
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COMMIT;
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-- test cursor with no chunks left after planning exclusion
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BEGIN;
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DECLARE c1 SCROLL CURSOR FOR SELECT * FROM cursor_test WHERE time > '2010-01-01';
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UPDATE cursor_test SET temp = 0.7 WHERE CURRENT OF c1;
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COMMIT;
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\set ON_ERROR_STOP 1
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SET timescaledb.enable_constraint_exclusion TO off;
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BEGIN;
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DECLARE c1 SCROLL CURSOR FOR SELECT * FROM cursor_test;
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FETCH NEXT FROM c1;
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UPDATE cursor_test SET temp = 0.7 WHERE CURRENT OF c1;
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COMMIT;
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