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Handle logical slot conflicts on standby

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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 6af1793954, 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 6af1793954 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
This commit is contained in:
Andres Freund
2023-04-07 23:11:28 -07:00
parent be87200efd
commit 26669757b6
20 changed files with 95 additions and 6 deletions
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15
src/backend/access/transam/xlog.c
View File

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