From 26669757b6a7665c1069e77e6472bd8550193ca6 Mon Sep 17 00:00:00 2001 From: Andres Freund Date: Fri, 7 Apr 2023 23:11:28 -0700 Subject: Handle logical slot conflicts on standby MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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 6af1793954e, 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 6af1793954e 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" Author: Andres Freund Author: Amit Khandekar (in an older version) Reviewed-by: "Drouvot, Bertrand" Reviewed-by: Andres Freund Reviewed-by: Robert Haas Reviewed-by: Fabrízio de Royes Mello Reviewed-by: Bharath Rupireddy Reviewed-by: Amit Kapila Reviewed-by: Alvaro Herrera Discussion: https://postgr.es/m/20230407075009.igg7be27ha2htkbt@awork3.anarazel.de --- src/backend/access/transam/xlog.c | 15 +++++++++++++++ 1 file changed, 15 insertions(+) (limited to 'src/backend/access/transam/xlog.c') diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c index 23903445293..13f83dd57d6 100644 --- a/src/backend/access/transam/xlog.c +++ b/src/backend/access/transam/xlog.c @@ -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; -- cgit v1.2.3