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Logical decoding's reorderbuffer keeps transactions in an LSN ordered list for efficiency. To make that's efficiently possible upper-level xids are forced to be logged before nested subtransaction xids. That only works though if these records are all looked at: Unfortunately we didn't do so for e.g. row level locks, which are otherwise uninteresting for logical decoding. This could lead to errors like: "ERROR: subxact logged without previous toplevel record". It's not sufficient to just look at row locking records, the xid could appear first due to a lot of other types of records (which will trigger the transaction to be marked logged with MarkCurrentTransactionIdLoggedIfAny). So invent infrastructure to tell reorderbuffer about xids seen, when they'd otherwise not pass through reorderbuffer.c. Reported-By: Jarred Ward Bug: #13844 Discussion: 20160105033249.1087.66040@wrigleys.postgresql.org Backpatch: 9.4, where logical decoding was added
23 lines
773 B
PL/PgSQL
23 lines
773 B
PL/PgSQL
-- predictability
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SET synchronous_commit = on;
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SELECT 'init' FROM pg_create_logical_replication_slot('regression_slot', 'test_decoding');
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-- bug #13844, xids in non-decoded records need to be inspected
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CREATE TABLE xact_test(data text);
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INSERT INTO xact_test VALUES ('before-test');
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BEGIN;
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-- perform operation in xact that creates and logs xid, but isn't decoded
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SELECT * FROM xact_test FOR UPDATE;
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SAVEPOINT foo;
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-- and now actually insert in subxact, xid is expected to be known
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INSERT INTO xact_test VALUES ('after-assignment');
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COMMIT;
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-- and now show those changes
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SELECT data FROM pg_logical_slot_get_changes('regression_slot', NULL, NULL, 'include-xids', '0', 'skip-empty-xacts', '1');
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DROP TABLE xact_test;
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SELECT pg_drop_replication_slot('regression_slot');
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