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Add option to enable two_phase commits via pg_create_logical_replication_slot.

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Commit 0aa8a01d04 extends the output plugin API to allow decoding of
prepared xacts and allowed the user to enable/disable the two-phase option
via pg_logical_slot_get_changes(). This can lead to a problem such that
the first time when it gets changes via pg_logical_slot_get_changes()
without two_phase option enabled it will not get the prepared even though
prepare is after consistent snapshot. Now next time during getting changes,
if the two_phase option is enabled it can skip prepare because by that
time start decoding point has been moved. So the user will only get commit
prepared.

Allow to enable/disable this option at the create slot time and default
will be false. It will break the existing slots which is fine in a major
release.

Author: Ajin Cherian
Reviewed-by: Amit Kapila and Vignesh C
Discussion: https://postgr.es/m/d0f60d60-133d-bf8d-bd70-47784d8fabf3@enterprisedb.com
This commit is contained in:
Amit Kapila
2021-03-03 07:28:43 +05:30
parent ee28cacf61
commit 19890a064e
20 changed files with 131 additions and 93 deletions
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10
contrib/test_decoding/sql/twophase_stream.sql
View File

@ -1,7 +1,7 @@
-- Test streaming of two-phase commits
SET synchronous_commit = on;
SELECT 'init' FROM pg_create_logical_replication_slot('regression_slot', 'test_decoding');
SELECT 'init' FROM pg_create_logical_replication_slot('regression_slot', 'test_decoding', false, true);
CREATE TABLE stream_test(data text);
@ -18,11 +18,11 @@ ROLLBACK TO s1;
INSERT INTO stream_test SELECT repeat('a', 10) || g.i FROM generate_series(1, 20) g(i);
PREPARE TRANSACTION 'test1';
-- should show the inserts after a ROLLBACK
SELECT data FROM pg_logical_slot_get_changes('regression_slot', NULL,NULL, 'two-phase-commit', '1', 'include-xids', '0', 'skip-empty-xacts', '1', 'stream-changes', '1');
SELECT data FROM pg_logical_slot_get_changes('regression_slot', NULL,NULL, 'include-xids', '0', 'skip-empty-xacts', '1', 'stream-changes', '1');
COMMIT PREPARED 'test1';
--should show the COMMIT PREPARED and the other changes in the transaction
SELECT data FROM pg_logical_slot_get_changes('regression_slot', NULL,NULL, 'two-phase-commit', '1', 'include-xids', '0', 'skip-empty-xacts', '1', 'stream-changes', '1');
SELECT data FROM pg_logical_slot_get_changes('regression_slot', NULL,NULL, 'include-xids', '0', 'skip-empty-xacts', '1', 'stream-changes', '1');
-- streaming test with sub-transaction and PREPARE/COMMIT PREPARED but with
-- filtered gid. gids with '_nodecode' will not be decoded at prepare time.
@ -35,11 +35,11 @@ ROLLBACK to s1;
INSERT INTO stream_test SELECT repeat('a', 10) || g.i FROM generate_series(1, 20) g(i);
PREPARE TRANSACTION 'test1_nodecode';
-- should NOT show inserts after a ROLLBACK
SELECT data FROM pg_logical_slot_get_changes('regression_slot', NULL,NULL, 'two-phase-commit', '1', 'include-xids', '0', 'skip-empty-xacts', '1', 'stream-changes', '1');
SELECT data FROM pg_logical_slot_get_changes('regression_slot', NULL,NULL, 'include-xids', '0', 'skip-empty-xacts', '1', 'stream-changes', '1');
COMMIT PREPARED 'test1_nodecode';
-- should show the inserts but not show a COMMIT PREPARED but a COMMIT
SELECT data FROM pg_logical_slot_get_changes('regression_slot', NULL,NULL, 'two-phase-commit', '1', 'include-xids', '0', 'skip-empty-xacts', '1', 'stream-changes', '1');
SELECT data FROM pg_logical_slot_get_changes('regression_slot', NULL,NULL, 'include-xids', '0', 'skip-empty-xacts', '1', 'stream-changes', '1');
DROP TABLE stream_test;
SELECT pg_drop_replication_slot('regression_slot');