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e4f16fda6e
Commit072ee847adtaught logical decoding to discard the changes of a transaction that is already known to be aborted when it is picked for eviction. That path reuses ReorderBufferTruncateTXN(), which marks every subtransaction that still has in-memory changes as streamed. Since nothing is streamed in that path, and the top-level transaction is never marked, a subtransaction ends up flagged as streamed even though the output plugin has never seen it. Decoding the subsequent abort record then makes ReorderBufferAbort() invoke the stream_abort callback for that subtransaction. For pgoutput this sends a Stream Abort ('A') message to a subscriber that requested streaming = off, and it does so regardless of the negotiated protocol version, so even a client speaking a version that predates transaction streaming receives a message it cannot parse. test_decoding dereferences a NULL pointer and crashes, since it allocates its per-transaction state in the begin or stream start callback, neither of which runs for a transaction discarded as aborted. This commit fixes this by marking a subtransaction as streamed only when it has changes and its top-level transaction is already marked as streamed. All streaming call sites mark the top-level transaction before truncating it, so their behavior is unchanged, while the abort-discard path never marks the top-level transaction and therefore now leaves its subtransactions unmarked. Backpatch to v18, where commit072ee847adwas introduced. Bug: #19616 Reported-by: Tyler Smart <tyler@smarts.io> Author: Andrey Rachitskiy <pl0h0yp1@gmail.com> Reviewed-by: Hayato Kuroda <kuroda.hayato@fujitsu.com> Reviewed-by: Fujii Masao <masao.fujii@gmail.com> Reviewed-by: Masahiko Sawada <sawada.mshk@gmail.com> Discussion: https://postgr.es/m/19616-f6153af509910853@postgresql.org Backpatch-through: 18
167 lines
6.2 KiB
Plaintext
167 lines
6.2 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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-- bug #19616
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--
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-- An aborted top-level transaction that is discarded at eviction must not
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-- leave its subtransactions marked as streamed. Otherwise, decoding its
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-- abort record invokes the stream abort callback for a subtransaction the
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-- output plugin has never seen, even though streaming was never requested.
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-- The trailing committed transaction is required to flush the ROLLBACK
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-- record; without it decoding would stop before reaching the abort.
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BEGIN;
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SAVEPOINT s;
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INSERT INTO stream_test VALUES ('subxact-change');
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RELEASE SAVEPOINT s;
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INSERT INTO stream_test SELECT 'toplevel-change' || g.i FROM generate_series(1, 5000) g(i);
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ROLLBACK;
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INSERT INTO stream_test VALUES ('after-abort');
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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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BEGIN
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table public.stream_test: INSERT: data[text]:'after-abort' i[integer]:null
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COMMIT
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(3 rows)
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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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