adhoc-035-failure-debugging.patch

diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index ca09c683f1..098310b23e 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -1883,6 +1883,7 @@ LogicalConfirmReceivedLocation(XLogRecPtr lsn)
 		{
 			SpinLockAcquire(&MyReplicationSlot->mutex);
 			MyReplicationSlot->effective_catalog_xmin = MyReplicationSlot->data.catalog_xmin;
+elog(LOG, "!!!LogicalConfirmReceivedLocation| MyReplicationSlot: %p, MyReplicationSlot->effective_catalog_xmin: %u", MyReplicationSlot, MyReplicationSlot->effective_catalog_xmin);
 			SpinLockRelease(&MyReplicationSlot->mutex);
 
 			ReplicationSlotsComputeRequiredXmin(false);
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 52da694c79..b072873b74 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -1380,6 +1380,7 @@ InvalidatePossiblyObsoleteSlot(ReplicationSlotInvalidationCause cause,
 
 		restart_lsn = s->data.restart_lsn;
 
+elog(LOG, "!!!InvalidatePossiblyObsoleteSlot| cause: %d, s->data.invalidated: %d", cause, s->data.invalidated);
 		/*
 		 * If the slot is already invalid or is a non conflicting slot, we
 		 * don't need to do anything.
@@ -1399,6 +1400,7 @@ InvalidatePossiblyObsoleteSlot(ReplicationSlotInvalidationCause cause,
 					/* invalid DB oid signals a shared relation */
 					if (dboid != InvalidOid && dboid != s->data.database)
 						break;
+elog(LOG, "!!!InvalidatePossiblyObsoleteSlot| RS_INVAL_HORIZON, s: %p, s->effective_xmin: %u, s->effective_catalog_xmin: %u, snapshotConflictHorizon: %u", s, s->effective_xmin, s->effective_catalog_xmin, snapshotConflictHorizon);
 					if (TransactionIdIsValid(s->effective_xmin) &&
 						TransactionIdPrecedesOrEquals(s->effective_xmin,
 													  snapshotConflictHorizon))
@@ -1417,6 +1419,7 @@ InvalidatePossiblyObsoleteSlot(ReplicationSlotInvalidationCause cause,
 			}
 		}
 
+elog(LOG, "!!!InvalidatePossiblyObsoleteSlot| conflict: %d", conflict);
 		/* if there's no conflict, we're done */
 		if (conflict == RS_INVAL_NONE)
 		{
@@ -1487,6 +1490,7 @@ InvalidatePossiblyObsoleteSlot(ReplicationSlotInvalidationCause cause,
 			 */
 			if (last_signaled_pid != active_pid)
 			{
+elog(LOG, "!!!InvalidatePossiblyObsoleteSlot| before ReportSlotInvalidation(..., true, ...)");
 				ReportSlotInvalidation(conflict, true, active_pid,
 									   slotname, restart_lsn,
 									   oldestLSN, snapshotConflictHorizon);
@@ -1532,6 +1536,7 @@ InvalidatePossiblyObsoleteSlot(ReplicationSlotInvalidationCause cause,
 			ReplicationSlotRelease();
 			pgstat_drop_replslot(s);
 
+elog(LOG, "!!!InvalidatePossiblyObsoleteSlot| before ReportSlotInvalidation(..., false, ...)");
 			ReportSlotInvalidation(conflict, false, active_pid,
 								   slotname, restart_lsn,
 								   oldestLSN, snapshotConflictHorizon);
@@ -1575,6 +1580,7 @@ InvalidateObsoleteReplicationSlots(ReplicationSlotInvalidationCause cause,
 	if (max_replication_slots == 0)
 		return invalidated;
 
+elog(LOG, "!!!InvalidateObsoleteReplicationSlots");
 	XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
 
 restart:
@@ -1586,10 +1592,12 @@ restart:
 		if (!s->in_use)
 			continue;
 
+elog(LOG, "!!!InvalidateObsoleteReplicationSlots| before InvalidatePossiblyObsoleteSlot");
 		if (InvalidatePossiblyObsoleteSlot(cause, s, oldestLSN, dboid,
 										   snapshotConflictHorizon,
 										   &invalidated))
 		{
+elog(LOG, "!!!InvalidateObsoleteReplicationSlots| InvalidatePossiblyObsoleteSlot returned true, invalidated: %d", invalidated);
 			/* if the lock was released, start from scratch */
 			goto restart;
 		}
diff --git a/src/backend/storage/ipc/standby.c b/src/backend/storage/ipc/standby.c
index d8755a106d..c4cb24cc50 100644
--- a/src/backend/storage/ipc/standby.c
+++ b/src/backend/storage/ipc/standby.c
@@ -500,9 +500,12 @@ ResolveRecoveryConflictWithSnapshot(TransactionId snapshotConflictHorizon,
 	 * reached, e.g. due to using a physical replication slot.
 	 */
 	if (wal_level >= WAL_LEVEL_LOGICAL && isCatalogRel)
+{
+//elog(LOG, "!!!ResolveRecoveryConflictWithSnapshot| RS_INVAL_HORIZON, snapshotConflictHorizon: %u, locator.dbOid: %d, locator.relNumber: %d", snapshotConflictHorizon, locator.dbOid, locator.relNumber);
 		InvalidateObsoleteReplicationSlots(RS_INVAL_HORIZON, 0, locator.dbOid,
 										   snapshotConflictHorizon);
 }
+}
 
 /*
  * Variant of ResolveRecoveryConflictWithSnapshot that works with