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19890a064e
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
112 lines
5.3 KiB
PL/PgSQL
112 lines
5.3 KiB
PL/PgSQL
-- Test prepared transactions. When two-phase-commit is enabled, transactions are
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-- decoded at PREPARE time rather than at COMMIT PREPARED time.
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SET synchronous_commit = on;
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SELECT 'init' FROM pg_create_logical_replication_slot('regression_slot', 'test_decoding', false, true);
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CREATE TABLE test_prepared1(id integer primary key);
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CREATE TABLE test_prepared2(id integer primary key);
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-- Test that decoding happens at PREPARE time when two-phase-commit is enabled.
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-- Decoding after COMMIT PREPARED must have all the commands in the transaction.
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BEGIN;
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INSERT INTO test_prepared1 VALUES (1);
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INSERT INTO test_prepared1 VALUES (2);
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-- should show nothing because the xact has not been prepared yet.
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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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PREPARE TRANSACTION 'test_prepared#1';
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-- should show both the above inserts and the PREPARE TRANSACTION.
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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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COMMIT PREPARED 'test_prepared#1';
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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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-- Test that rollback of a prepared xact is decoded.
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BEGIN;
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INSERT INTO test_prepared1 VALUES (3);
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PREPARE TRANSACTION 'test_prepared#2';
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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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ROLLBACK PREPARED 'test_prepared#2';
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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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-- Test prepare of a xact containing ddl. Leaving xact uncommitted for next test.
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BEGIN;
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ALTER TABLE test_prepared1 ADD COLUMN data text;
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INSERT INTO test_prepared1 VALUES (4, 'frakbar');
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PREPARE TRANSACTION 'test_prepared#3';
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-- confirm that exclusive lock from the ALTER command is held on test_prepared1 table
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SELECT 'test_prepared_1' AS relation, locktype, mode
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FROM pg_locks
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WHERE locktype = 'relation'
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AND relation = 'test_prepared1'::regclass;
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-- The insert should show the newly altered column but not the DDL.
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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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-- Test that we decode correctly while an uncommitted prepared xact
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-- with ddl exists.
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--
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-- Use a separate table for the concurrent transaction because the lock from
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-- the ALTER will stop us inserting into the other one.
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--
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INSERT INTO test_prepared2 VALUES (5);
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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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COMMIT PREPARED 'test_prepared#3';
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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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-- make sure stuff still works
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INSERT INTO test_prepared1 VALUES (6);
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INSERT INTO test_prepared2 VALUES (7);
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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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-- Check 'CLUSTER' (as operation that hold exclusive lock) doesn't block
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-- logical decoding.
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BEGIN;
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INSERT INTO test_prepared1 VALUES (8, 'othercol');
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CLUSTER test_prepared1 USING test_prepared1_pkey;
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INSERT INTO test_prepared1 VALUES (9, 'othercol2');
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PREPARE TRANSACTION 'test_prepared_lock';
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SELECT 'test_prepared1' AS relation, locktype, mode
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FROM pg_locks
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WHERE locktype = 'relation'
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AND relation = 'test_prepared1'::regclass;
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-- The above CLUSTER command shouldn't cause a timeout on 2pc decoding.
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SET statement_timeout = '180s';
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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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RESET statement_timeout;
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COMMIT PREPARED 'test_prepared_lock';
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-- consume the commit
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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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-- Test savepoints and sub-xacts. Creating savepoints will create
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-- sub-xacts implicitly.
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BEGIN;
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CREATE TABLE test_prepared_savepoint (a int);
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INSERT INTO test_prepared_savepoint VALUES (1);
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SAVEPOINT test_savepoint;
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INSERT INTO test_prepared_savepoint VALUES (2);
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ROLLBACK TO SAVEPOINT test_savepoint;
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PREPARE TRANSACTION 'test_prepared_savepoint';
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-- should show only 1, not 2
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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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COMMIT PREPARED 'test_prepared_savepoint';
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-- consume the commit
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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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-- Test that a GID containing "_nodecode" gets decoded at commit prepared time.
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BEGIN;
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INSERT INTO test_prepared1 VALUES (20);
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PREPARE TRANSACTION 'test_prepared_nodecode';
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-- should show nothing
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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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COMMIT PREPARED 'test_prepared_nodecode';
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-- should be decoded now
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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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-- Test 8:
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-- cleanup and make sure results are also empty
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DROP TABLE test_prepared1;
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DROP TABLE test_prepared2;
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-- show results. There should be nothing to show
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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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SELECT pg_drop_replication_slot('regression_slot');
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