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src/test/isolation/specs/serializable-parallel.spec
47 строк
1 KB
David Rowley
Rename force_parallel_mode to debug_parallel_query
15 фев 2023, 11:21
15 фев 2023, 11:21
5352ca2
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# The example from the paper "A read-only transaction anomaly under snapshot # isolation"[1]. # # Here we test that serializable snapshot isolation (SERIALIZABLE) doesn't # suffer from the anomaly, because s2 is aborted upon detection of a cycle. # In this case the read only query s3 happens to be running in a parallel # worker. # # [1] http://www.cs.umb.edu/~poneil/ROAnom.pdf setup { CREATE TABLE bank_account (id TEXT PRIMARY KEY, balance DECIMAL NOT NULL); INSERT INTO bank_account (id, balance) VALUES ('X', 0), ('Y', 0); } teardown { DROP TABLE bank_account; } session s1 setup { BEGIN TRANSACTION ISOLATION LEVEL SERIALIZABLE; } step s1ry { SELECT balance FROM bank_account WHERE id = 'Y'; } step s1wy { UPDATE bank_account SET balance = 20 WHERE id = 'Y'; } step s1c { COMMIT; } session s2 setup { BEGIN TRANSACTION ISOLATION LEVEL SERIALIZABLE; } step s2rx { SELECT balance FROM bank_account WHERE id = 'X'; } step s2ry { SELECT balance FROM bank_account WHERE id = 'Y'; } step s2wx { UPDATE bank_account SET balance = -11 WHERE id = 'X'; } step s2c { COMMIT; } session s3 setup { BEGIN TRANSACTION ISOLATION LEVEL SERIALIZABLE; SET debug_parallel_query = on; } step s3r { SELECT id, balance FROM bank_account WHERE id IN ('X', 'Y') ORDER BY id; } step s3c { COMMIT; } # without s3, s1 and s2 commit permutation s2rx s2ry s1ry s1wy s1c s2wx s2c s3c # once s3 observes the data committed by s1, a cycle is created and s2 aborts permutation s2rx s2ry s1ry s1wy s1c s3r s3c s2wx