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 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" <[email protected]>
Author: Andres Freund <[email protected]>
Author: Amit Khandekar <[email protected]> (in an older version)
Reviewed-by: "Drouvot, Bertrand" <[email protected]>
Reviewed-by: Andres Freund <[email protected]>
Reviewed-by: Robert Haas <[email protected]>
Reviewed-by: Fabrízio de Royes Mello <[email protected]>
Reviewed-by: Bharath Rupireddy <[email protected]>
Reviewed-by: Amit Kapila <[email protected]>
Reviewed-by: Alvaro Herrera <[email protected]>
Discussion: https://postgr.es/m/[email protected]

1 files changed, 3 insertions, 0 deletions

diff --git a/src/backend/access/heap/heapam.c b/src/backend/access/heap/heapam.c
index 8b13e3f8925..f389ceee1ea 100644
--- a/src/backend/access/heap/heapam.c
+++ b/src/backend/access/heap/heapam.c
@@ -8769,6 +8769,7 @@ heap_xlog_prune(XLogReaderState *record)
 	 */
 	if (InHotStandby)
 		ResolveRecoveryConflictWithSnapshot(xlrec->snapshotConflictHorizon,
+											xlrec->isCatalogRel,
 											rlocator);
 
 	/*
@@ -8940,6 +8941,7 @@ heap_xlog_visible(XLogReaderState *record)
 	 */
 	if (InHotStandby)
 		ResolveRecoveryConflictWithSnapshot(xlrec->snapshotConflictHorizon,
+											xlrec->flags & VISIBILITYMAP_XLOG_CATALOG_REL,
 											rlocator);
 
 	/*
@@ -9061,6 +9063,7 @@ heap_xlog_freeze_page(XLogReaderState *record)
 
 		XLogRecGetBlockTag(record, 0, &rlocator, NULL, NULL);
 		ResolveRecoveryConflictWithSnapshot(xlrec->snapshotConflictHorizon,
+											xlrec->isCatalogRel,
 											rlocator);
 	}