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072ee847ad
Previously, transaction aborts were detected concurrently only during system catalog scans while replaying a transaction in streaming mode. This commit adds an additional CLOG lookup to check the transaction status, allowing the logical decoding to skip changes also when it doesn't touch system catalogs, if the transaction is already aborted. This optimization enhances logical decoding performance, especially for large transactions that have already been rolled back, as it avoids unnecessary disk or network I/O. To avoid potential slowdowns caused by frequent CLOG lookups for small transactions (most of which commit), the CLOG lookup is performed only for large transactions before eviction. The performance benchmark results showed there is not noticeable performance regression due to CLOG lookups. Reviewed-by: Amit Kapila, Peter Smith, Vignesh C, Ajin Cherian Reviewed-by: Dilip Kumar, Andres Freund Discussion: https://postgr.es/m/CAD21AoDht9Pz_DFv_R2LqBTBbO4eGrpa9Vojmt5z5sEx3XwD7A@mail.gmail.com
144 lines
5.2 KiB
Plaintext
144 lines
5.2 KiB
Plaintext
SET synchronous_commit = on;
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SELECT 'init' FROM pg_create_logical_replication_slot('regression_slot', 'test_decoding');
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?column?
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----------
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init
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(1 row)
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CREATE TABLE stream_test(data text);
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-- consume 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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data
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------
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(0 rows)
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-- streaming test with sub-transaction
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BEGIN;
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savepoint s1;
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SELECT 'msg5' FROM pg_logical_emit_message(true, 'test', repeat('a', 50));
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?column?
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----------
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msg5
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(1 row)
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INSERT INTO stream_test SELECT repeat('a', 2000) || g.i FROM generate_series(1, 35) g(i);
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TRUNCATE table stream_test;
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rollback to s1;
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INSERT INTO stream_test SELECT repeat('a', 10) || g.i FROM generate_series(1, 20) g(i);
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COMMIT;
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SELECT data FROM pg_logical_slot_get_changes('regression_slot', NULL,NULL, 'include-xids', '0', 'skip-empty-xacts', '1', 'stream-changes', '1');
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data
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----------------------------------------------------------
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opening a streamed block for transaction
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streaming message: transactional: 1 prefix: test, sz: 50
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closing a streamed block for transaction
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aborting streamed (sub)transaction
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opening a streamed block for transaction
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streaming change for transaction
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streaming change for transaction
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streaming change for transaction
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streaming change for transaction
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streaming change for transaction
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streaming change for transaction
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streaming change for transaction
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streaming change for transaction
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streaming change for transaction
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streaming change for transaction
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streaming change for transaction
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streaming change for transaction
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streaming change for transaction
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streaming change for transaction
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streaming change for transaction
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streaming change for transaction
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streaming change for transaction
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streaming change for transaction
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streaming change for transaction
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streaming change for transaction
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closing a streamed block for transaction
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committing streamed transaction
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(27 rows)
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-- streaming test for toast changes
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ALTER TABLE stream_test ALTER COLUMN data set storage external;
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-- consume 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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data
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------
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(0 rows)
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INSERT INTO stream_test SELECT repeat('a', 6000) || g.i FROM generate_series(1, 10) g(i);
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SELECT data FROM pg_logical_slot_get_changes('regression_slot', NULL,NULL, 'include-xids', '0', 'skip-empty-xacts', '1', 'stream-changes', '1');
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data
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------------------------------------------
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opening a streamed block for transaction
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streaming change for transaction
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streaming change for transaction
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streaming change for transaction
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streaming change for transaction
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streaming change for transaction
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streaming change for transaction
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streaming change for transaction
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streaming change for transaction
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streaming change for transaction
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streaming change for transaction
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closing a streamed block for transaction
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committing streamed transaction
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(13 rows)
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-- streaming test for toast with multi-insert
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\COPY stream_test FROM STDIN
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SELECT data FROM pg_logical_slot_get_changes('regression_slot', NULL,NULL, 'include-xids', '0', 'skip-empty-xacts', '1', 'stream-changes', '1');
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data
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------------------------------------------
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opening a streamed block for transaction
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streaming change for transaction
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streaming change for transaction
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streaming change for transaction
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streaming change for transaction
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streaming change for transaction
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streaming change for transaction
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streaming change for transaction
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streaming change for transaction
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streaming change for transaction
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streaming change for transaction
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streaming change for transaction
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closing a streamed block for transaction
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opening a streamed block for transaction
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streaming change for transaction
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closing a streamed block for transaction
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committing streamed transaction
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(17 rows)
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/*
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* Test concurrent abort with toast data. When streaming the second insertion, we
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* detect that the subtransaction was aborted, and reset the transaction while having
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* the TOAST changes in memory, resulting in deallocating both decoded changes and
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* TOAST reconstruction data. Memory usage counters must be updated correctly.
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*
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* Set debug_logical_replication_streaming to 'immediate' to disable the transaction
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* status check happening before streaming the second insertion, so we can detect a
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* concurrent abort while streaming.
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*/
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SET debug_logical_replication_streaming = immediate;
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BEGIN;
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INSERT INTO stream_test SELECT repeat(string_agg(to_char(g.i, 'FM0000'), ''), 50) FROM generate_series(1, 500) g(i);
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ALTER TABLE stream_test ADD COLUMN i INT;
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SAVEPOINT s1;
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INSERT INTO stream_test(data, i) SELECT repeat(string_agg(to_char(g.i, 'FM0000'), ''), 50), 1 FROM generate_series(1, 500) g(i);
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ROLLBACK TO s1;
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COMMIT;
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SELECT count(*) FROM pg_logical_slot_get_changes('regression_slot', NULL, NULL, 'include-xids', '0', 'skip-empty-xacts', '1', 'stream-changes', '1');
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count
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-------
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5
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(1 row)
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RESET debug_logical_replication_streaming;
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DROP TABLE stream_test;
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SELECT pg_drop_replication_slot('regression_slot');
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pg_drop_replication_slot
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--------------------------
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(1 row)
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