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Handle logical slot conflicts on standby
During WAL replay on the standby, when a conflict with a logical slot is identified, invalidate such slots. There are two sources of conflicts: 1) Using the information added in 6af1793, logical slots are invalidated if required rows are removed 2) wal_level on the primary server is reduced to below logical Uses the infrastructure introduced in the prior commit. FIXME: add commit reference. Change InvalidatePossiblyObsoleteSlot() to use a recovery conflict to interrupt use of a slot, if called in the startup process. The new recovery conflict is added to pg_stat_database_conflicts, as confl_active_logicalslot. See 6af1793 for an overall design of logical decoding on a standby. Bumps catversion for the addition of the pg_stat_database_conflicts column. Bumps PGSTAT_FILE_FORMAT_ID for the same reason. Author: "Drouvot, Bertrand" <bertranddrouvot.pg@gmail.com> Author: Andres Freund <andres@anarazel.de> Author: Amit Khandekar <amitdkhan.pg@gmail.com> (in an older version) Reviewed-by: "Drouvot, Bertrand" <bertranddrouvot.pg@gmail.com> Reviewed-by: Andres Freund <andres@anarazel.de> Reviewed-by: Robert Haas <robertmhaas@gmail.com> Reviewed-by: Fabrízio de Royes Mello <fabriziomello@gmail.com> Reviewed-by: Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com> Reviewed-by: Amit Kapila <amit.kapila16@gmail.com> Reviewed-by: Alvaro Herrera <alvherre@alvh.no-ip.org> Discussion: https://postgr.es/m/20230407075009.igg7be27ha2htkbt@awork3.anarazel.de
1 parent be87200 commit 2666975

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+95
-6
lines changed

20 files changed

+95
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lines changed

‎doc/src/sgml/monitoring.sgml

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@@ -4742,6 +4742,17 @@ SELECT pid, wait_event_type, wait_event FROM pg_stat_activity WHERE wait_event i
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deadlocks
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</para></entry>
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</row>
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<row>
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<entry role="catalog_table_entry"><para role="column_definition">
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<structfield>confl_active_logicalslot</structfield> <type>bigint</type>
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</para>
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<para>
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Number of uses of logical slots in this database that have been
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canceled due to old snapshots or a too low <xref linkend="guc-wal-level"/>
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on the primary
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</para></entry>
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</row>
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</tbody>
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</tgroup>
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</table>

‎src/backend/access/gist/gistxlog.c

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@@ -197,6 +197,7 @@ gistRedoDeleteRecord(XLogReaderState *record)
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XLogRecGetBlockTag(record, 0, &rlocator, NULL, NULL);
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ResolveRecoveryConflictWithSnapshot(xldata->snapshotConflictHorizon,
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xldata->isCatalogRel,
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rlocator);
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}
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@@ -390,6 +391,7 @@ gistRedoPageReuse(XLogReaderState *record)
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*/
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if (InHotStandby)
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ResolveRecoveryConflictWithSnapshotFullXid(xlrec->snapshotConflictHorizon,
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xlrec->isCatalogRel,
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xlrec->locator);
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}
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‎src/backend/access/hash/hash_xlog.c

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@@ -1003,6 +1003,7 @@ hash_xlog_vacuum_one_page(XLogReaderState *record)
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XLogRecGetBlockTag(record, 0, &rlocator, NULL, NULL);
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ResolveRecoveryConflictWithSnapshot(xldata->snapshotConflictHorizon,
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xldata->isCatalogRel,
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rlocator);
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}
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‎src/backend/access/heap/heapam.c

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@@ -8769,6 +8769,7 @@ heap_xlog_prune(XLogReaderState *record)
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*/
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if (InHotStandby)
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ResolveRecoveryConflictWithSnapshot(xlrec->snapshotConflictHorizon,
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xlrec->isCatalogRel,
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rlocator);
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/*
@@ -8940,6 +8941,7 @@ heap_xlog_visible(XLogReaderState *record)
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*/
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if (InHotStandby)
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ResolveRecoveryConflictWithSnapshot(xlrec->snapshotConflictHorizon,
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xlrec->flags & VISIBILITYMAP_XLOG_CATALOG_REL,
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rlocator);
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/*
@@ -9061,6 +9063,7 @@ heap_xlog_freeze_page(XLogReaderState *record)
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XLogRecGetBlockTag(record, 0, &rlocator, NULL, NULL);
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ResolveRecoveryConflictWithSnapshot(xlrec->snapshotConflictHorizon,
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xlrec->isCatalogRel,
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rlocator);
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}
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‎src/backend/access/nbtree/nbtxlog.c

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@@ -669,6 +669,7 @@ btree_xlog_delete(XLogReaderState *record)
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XLogRecGetBlockTag(record, 0, &rlocator, NULL, NULL);
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ResolveRecoveryConflictWithSnapshot(xlrec->snapshotConflictHorizon,
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xlrec->isCatalogRel,
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rlocator);
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}
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@@ -1007,6 +1008,7 @@ btree_xlog_reuse_page(XLogReaderState *record)
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if (InHotStandby)
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ResolveRecoveryConflictWithSnapshotFullXid(xlrec->snapshotConflictHorizon,
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xlrec->isCatalogRel,
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xlrec->locator);
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}
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‎src/backend/access/spgist/spgxlog.c

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@@ -879,6 +879,7 @@ spgRedoVacuumRedirect(XLogReaderState *record)
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XLogRecGetBlockTag(record, 0, &locator, NULL, NULL);
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ResolveRecoveryConflictWithSnapshot(xldata->snapshotConflictHorizon,
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xldata->isCatalogRel,
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locator);
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}
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‎src/backend/access/transam/xlog.c

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@@ -7970,6 +7970,21 @@ xlog_redo(XLogReaderState *record)
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/* Update our copy of the parameters in pg_control */
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memcpy(&xlrec, XLogRecGetData(record), sizeof(xl_parameter_change));
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/*
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* Invalidate logical slots if we are in hot standby and the primary
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* does not have a WAL level sufficient for logical decoding. No need
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* to search for potentially conflicting logically slots if standby is
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* running with wal_level lower than logical, because in that case, we
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* would have either disallowed creation of logical slots or
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* invalidated existing ones.
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*/
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if (InRecovery && InHotStandby &&
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xlrec.wal_level < WAL_LEVEL_LOGICAL &&
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wal_level >= WAL_LEVEL_LOGICAL)
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InvalidateObsoleteReplicationSlots(RS_INVAL_WAL_LEVEL,
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0, InvalidOid,
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InvalidTransactionId);
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LWLockAcquire(ControlFileLock, LW_EXCLUSIVE);
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ControlFile->MaxConnections = xlrec.MaxConnections;
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ControlFile->max_worker_processes = xlrec.max_worker_processes;

‎src/backend/catalog/system_views.sql

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@@ -1069,7 +1069,8 @@ CREATE VIEW pg_stat_database_conflicts AS
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pg_stat_get_db_conflict_lock(D.oid) AS confl_lock,
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pg_stat_get_db_conflict_snapshot(D.oid) AS confl_snapshot,
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pg_stat_get_db_conflict_bufferpin(D.oid) AS confl_bufferpin,
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pg_stat_get_db_conflict_startup_deadlock(D.oid) AS confl_deadlock
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pg_stat_get_db_conflict_startup_deadlock(D.oid) AS confl_deadlock,
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pg_stat_get_db_conflict_logicalslot(D.oid) AS confl_active_logicalslot
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FROM pg_database D;
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CREATE VIEW pg_stat_user_functions AS

‎src/backend/replication/slot.c

Lines changed: 7 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -1442,7 +1442,13 @@ InvalidatePossiblyObsoleteSlot(ReplicationSlotInvalidationCause cause,
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slotname, restart_lsn,
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oldestLSN, snapshotConflictHorizon);
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(void) kill(active_pid, SIGTERM);
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if (MyBackendType == B_STARTUP)
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(void) SendProcSignal(active_pid,
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PROCSIG_RECOVERY_CONFLICT_LOGICALSLOT,
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InvalidBackendId);
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else
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(void) kill(active_pid, SIGTERM);
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last_signaled_pid = active_pid;
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}
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‎src/backend/storage/ipc/procsignal.c

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@@ -673,6 +673,9 @@ procsignal_sigusr1_handler(SIGNAL_ARGS)
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if (CheckProcSignal(PROCSIG_RECOVERY_CONFLICT_SNAPSHOT))
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RecoveryConflictInterrupt(PROCSIG_RECOVERY_CONFLICT_SNAPSHOT);
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if (CheckProcSignal(PROCSIG_RECOVERY_CONFLICT_LOGICALSLOT))
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RecoveryConflictInterrupt(PROCSIG_RECOVERY_CONFLICT_LOGICALSLOT);
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if (CheckProcSignal(PROCSIG_RECOVERY_CONFLICT_STARTUP_DEADLOCK))
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RecoveryConflictInterrupt(PROCSIG_RECOVERY_CONFLICT_STARTUP_DEADLOCK);
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