42 lines
1.1 KiB
Python
42 lines
1.1 KiB
Python
# Test SKIP LOCKED with multixact locks.
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setup
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{
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CREATE TABLE queue (
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id int PRIMARY KEY,
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data text NOT NULL,
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status text NOT NULL
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);
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INSERT INTO queue VALUES (1, 'foo', 'NEW'), (2, 'bar', 'NEW');
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}
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teardown
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{
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DROP TABLE queue;
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}
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session s1
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setup { BEGIN; }
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step s1a { SELECT * FROM queue ORDER BY id FOR SHARE SKIP LOCKED LIMIT 1; }
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step s1b { COMMIT; }
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session s2
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setup { BEGIN; }
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step s2a { SELECT * FROM queue ORDER BY id FOR SHARE SKIP LOCKED LIMIT 1; }
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step s2b { SELECT * FROM queue ORDER BY id FOR UPDATE SKIP LOCKED LIMIT 1; }
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step s2c { COMMIT; }
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# s1 and s2 both get SHARE lock, creating a multixact lock, then s2
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# tries to update to UPDATE but skips the record because it can't
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# acquire a multixact lock
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permutation s1a s2a s2b s1b s2c
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# the same but with the SHARE locks acquired in a different order, so
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# s2 again skips because it can't acquired a multixact lock
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permutation s2a s1a s2b s1b s2c
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# s2 acquires SHARE then UPDATE, then s1 tries to acquire SHARE but
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# can't so skips the first record because it can't acquire a regular
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# lock
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permutation s2a s2b s1a s1b s2c
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