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postgresql/contrib/test_decoding/expected/catalog_change_snapshot.out

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Fix catalog lookup with the wrong snapshot during logical decoding. Previously, we relied on HEAP2_NEW_CID records and XACT_INVALIDATION records to know if the transaction has modified the catalog, and that information is not serialized to snapshot. Therefore, after the restart, if the logical decoding decodes only the commit record of the transaction that has actually modified a catalog, we will miss adding its XID to the snapshot. Thus, we will end up looking at catalogs with the wrong snapshot. To fix this problem, this changes the snapshot builder so that it remembers the last-running-xacts list of the decoded RUNNING_XACTS record after restoring the previously serialized snapshot. Then, we mark the transaction as containing catalog changes if it's in the list of initial running transactions and its commit record has XACT_XINFO_HAS_INVALS. To avoid ABI breakage, we store the array of the initial running transactions in the static variables InitialRunningXacts and NInitialRunningXacts, instead of storing those in SnapBuild or ReorderBuffer. This approach has a false positive; we could end up adding the transaction that didn't change catalog to the snapshot since we cannot distinguish whether the transaction has catalog changes only by checking the COMMIT record. It doesn't have the information on which (sub) transaction has catalog changes, and XACT_XINFO_HAS_INVALS doesn't necessarily indicate that the transaction has catalog change. But that won't be a problem since we use snapshot built during decoding only to read system catalogs. On the master branch, we took a more future-proof approach by writing catalog modifying transactions to the serialized snapshot which avoids the above false positive. But we cannot backpatch it because of a change in the SnapBuild. Reported-by: Mike Oh Author: Masahiko Sawada Reviewed-by: Amit Kapila, Shi yu, Takamichi Osumi, Kyotaro Horiguchi, Bertrand Drouvot, Ahsan Hadi Backpatch-through: 10 Discussion: https://postgr.es/m/81D0D8B0-E7C4-4999-B616-1E5004DBDCD2%40amazon.com
2022-08-11 05:39:36 +02:00
Parsed test spec with 2 sessions
starting permutation: s0_init s0_begin s0_savepoint s0_truncate s1_checkpoint s1_get_changes s0_commit s0_begin s0_insert s1_checkpoint s1_get_changes s0_commit s1_get_changes
step s0_init: SELECT 'init' FROM pg_create_logical_replication_slot('isolation_slot', 'test_decoding');
?column?
--------
init
(1 row)
step s0_begin: BEGIN;
step s0_savepoint: SAVEPOINT sp1;
step s0_truncate: TRUNCATE tbl1;
step s1_checkpoint: CHECKPOINT;
step s1_get_changes: SELECT data FROM pg_logical_slot_get_changes('isolation_slot', NULL, NULL, 'skip-empty-xacts', '1', 'include-xids', '0');
data
----
(0 rows)
step s0_commit: COMMIT;
step s0_begin: BEGIN;
step s0_insert: INSERT INTO tbl1 VALUES (1);
step s1_checkpoint: CHECKPOINT;
step s1_get_changes: SELECT data FROM pg_logical_slot_get_changes('isolation_slot', NULL, NULL, 'skip-empty-xacts', '1', 'include-xids', '0');
data
---------------------------------------
BEGIN
table public.tbl1: TRUNCATE: (no-flags)
COMMIT
(3 rows)
step s0_commit: COMMIT;
step s1_get_changes: SELECT data FROM pg_logical_slot_get_changes('isolation_slot', NULL, NULL, 'skip-empty-xacts', '1', 'include-xids', '0');
data
-------------------------------------------------------------
BEGIN
table public.tbl1: INSERT: val1[integer]:1 val2[integer]:null
COMMIT
(3 rows)
?column?
--------
stop
(1 row)
Fix assertion failures while processing NEW_CID record in logical decoding. When the logical decoding restarts from NEW_CID, since there is no association between the top transaction and its subtransaction, both are created as top transactions and have the same LSN. This caused the assertion failure in AssertTXNLsnOrder(). This patch skips the assertion check until we reach the LSN at which we start decoding the contents of the transaction, specifically start_decoding_at LSN in SnapBuild. This is okay because we don't guarantee to make the association between top transaction and subtransaction until we try to decode the actual contents of transaction. The ordering of the records prior to the start_decoding_at LSN should have been checked before the restart. The other assertion failure is due to the reason that we forgot to track that we have considered top-level transaction id in the list of catalog changing transactions that were committed when one of its subtransactions is marked as containing catalog change. Reported-by: Tomas Vondra, Osumi Takamichi Author: Masahiko Sawada, Kuroda Hayato Reviewed-by: Amit Kapila, Dilip Kumar, Kuroda Hayato, Kyotaro Horiguchi, Masahiko Sawada Backpatch-through: 10 Discussion: https://postgr.es/m/a89b46b6-0239-2fd5-71a9-b19b1f7a7145%40enterprisedb.com Discussion: https://postgr.es/m/TYCPR01MB83733C6CEAE47D0280814D5AED7A9%40TYCPR01MB8373.jpnprd01.prod.outlook.com
2022-10-20 05:46:28 +02:00
starting permutation: s0_init s0_begin s0_savepoint s0_insert s1_checkpoint s1_get_changes s0_insert2 s0_commit s0_begin s0_insert s1_checkpoint s1_get_changes s0_commit s1_get_changes
step s0_init: SELECT 'init' FROM pg_create_logical_replication_slot('isolation_slot', 'test_decoding');
?column?
--------
init
(1 row)
step s0_begin: BEGIN;
step s0_savepoint: SAVEPOINT sp1;
step s0_insert: INSERT INTO tbl1 VALUES (1);
step s1_checkpoint: CHECKPOINT;
step s1_get_changes: SELECT data FROM pg_logical_slot_get_changes('isolation_slot', NULL, NULL, 'skip-empty-xacts', '1', 'include-xids', '0');
data
----
(0 rows)
step s0_insert2: INSERT INTO user_cat VALUES (1);
step s0_commit: COMMIT;
step s0_begin: BEGIN;
step s0_insert: INSERT INTO tbl1 VALUES (1);
step s1_checkpoint: CHECKPOINT;
step s1_get_changes: SELECT data FROM pg_logical_slot_get_changes('isolation_slot', NULL, NULL, 'skip-empty-xacts', '1', 'include-xids', '0');
data
-------------------------------------------------------------
BEGIN
table public.tbl1: INSERT: val1[integer]:1 val2[integer]:null
table public.user_cat: INSERT: val1[integer]:1
COMMIT
(4 rows)
step s0_commit: COMMIT;
step s1_get_changes: SELECT data FROM pg_logical_slot_get_changes('isolation_slot', NULL, NULL, 'skip-empty-xacts', '1', 'include-xids', '0');
data
-------------------------------------------------------------
BEGIN
table public.tbl1: INSERT: val1[integer]:1 val2[integer]:null
COMMIT
(3 rows)
?column?
--------
stop
(1 row)