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src/test/isolation/specs/skip-locked-2.spec
41 строка
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Tom Lane
Allow non-quoted identifiers as isolation test session/step names.
24 июн 2021, 01:41
24 июн 2021, 01:41
a443c1b
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# Test SKIP LOCKED with multixact locks. setup { CREATE TABLE queue ( id int PRIMARY KEY, data text NOT NULL, status text NOT NULL ); INSERT INTO queue VALUES (1, 'foo', 'NEW'), (2, 'bar', 'NEW'); } teardown { DROP TABLE queue; } session s1 setup { BEGIN; } step s1a { SELECT * FROM queue ORDER BY id FOR SHARE SKIP LOCKED LIMIT 1; } step s1b { COMMIT; } session s2 setup { BEGIN; } step s2a { SELECT * FROM queue ORDER BY id FOR SHARE SKIP LOCKED LIMIT 1; } step s2b { SELECT * FROM queue ORDER BY id FOR UPDATE SKIP LOCKED LIMIT 1; } step s2c { COMMIT; } # s1 and s2 both get SHARE lock, creating a multixact lock, then s2 # tries to update to UPDATE but skips the record because it can't # acquire a multixact lock permutation s1a s2a s2b s1b s2c # the same but with the SHARE locks acquired in a different order, so # s2 again skips because it can't acquired a multixact lock permutation s2a s1a s2b s1b s2c # s2 acquires SHARE then UPDATE, then s1 tries to acquire SHARE but # can't so skips the first record because it can't acquire a regular # lock permutation s2a s2b s1a s1b s2c