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Fix parallel worker tracking of new catalog relfilenumbers.

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Reunite RestorePendingSyncs() with RestoreRelationMap().  If
RelationInitPhysicalAddr() ran after RestoreRelationMap() but before
RestorePendingSyncs(), the relcache entry could cause RelationNeedsWAL()
to return true erroneously.  Trouble required commands of the current
transaction to include REINDEX or CLUSTER of a system catalog.  The
parallel leader correctly derived RelationNeedsWAL()==false from the new
relfilenumber, but the worker saw RelationNeedsWAL()==true.  Worker
MarkBufferDirtyHint() then wrote unwanted WAL.  Recovery of that
unwanted WAL could lose tuples like the system could before commit
c6b92041d3 introduced this tracking.
RestorePendingSyncs() and RestoreRelationMap() were adjacent till commit
126ec0bc76, so no back-patch for now.

Reviewed by Tom Lane.

Discussion: https://postgr.es/m/20241019232815.c6.nmisch@google.com
This commit is contained in:
Noah Misch
2024-10-24 09:16:38 -07:00
parent e947224cbb
commit 67bab53d64
1 changed files with 7 additions and 11 deletions
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18
src/backend/access/transam/parallel.c
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@ -1421,17 +1421,18 @@ ParallelWorkerMain(Datum main_arg)
StartParallelWorkerTransaction(tstatespace);
/*
* Restore relmapper and reindex state early, since these affect catalog
* access. Ideally we'd do this even before calling InitPostgres, but
* that has order-of-initialization problems, and also the relmapper would
* get confused during the CommitTransactionCommand call above.
* Restore state that affects catalog access. Ideally we'd do this even
* before calling InitPostgres, but that has order-of-initialization
* problems, and also the relmapper would get confused during the
* CommitTransactionCommand call above.
*/
pendingsyncsspace = shm_toc_lookup(toc, PARALLEL_KEY_PENDING_SYNCS,
false);
RestorePendingSyncs(pendingsyncsspace);
relmapperspace = shm_toc_lookup(toc, PARALLEL_KEY_RELMAPPER_STATE, false);
RestoreRelationMap(relmapperspace);
reindexspace = shm_toc_lookup(toc, PARALLEL_KEY_REINDEX_STATE, false);
RestoreReindexState(reindexspace);
/* Restore combo CID state. */
combocidspace = shm_toc_lookup(toc, PARALLEL_KEY_COMBO_CID, false);
RestoreComboCIDState(combocidspace);
@ -1488,11 +1489,6 @@ ParallelWorkerMain(Datum main_arg)
SetTempNamespaceState(fps->temp_namespace_id,
fps->temp_toast_namespace_id);
/* Restore pending syncs. */
pendingsyncsspace = shm_toc_lookup(toc, PARALLEL_KEY_PENDING_SYNCS,
false);
RestorePendingSyncs(pendingsyncsspace);
/* Restore uncommitted enums. */
uncommittedenumsspace = shm_toc_lookup(toc, PARALLEL_KEY_UNCOMMITTEDENUMS,
false);