Standardize rmgrdesc recovery conflict XID output.

Standardize on the name snapshotConflictHorizon for all XID fields from
WAL records that generate recovery conflicts when in hot standby mode.
This supersedes the previous latestRemovedXid naming convention.

The new naming convention places emphasis on how the values are actually
used by REDO routines.  How the values are generated during original
execution (details of which vary by record type) is deemphasized.  Users
of tools like pg_waldump can now grep for snapshotConflictHorizon to see
all potential sources of recovery conflicts in a standardized way,
without necessarily having to consider which specific record types might
be involved.

Also bring a couple of WAL record types that didn't follow any kind of
naming convention into line.  These are heapam's VISIBLE record type and
SP-GiST's VACUUM_REDIRECT record type.  Now every WAL record whose REDO
routine calls ResolveRecoveryConflictWithSnapshot() passes through the
snapshotConflictHorizon field from its WAL record.  This is follow-up
work to the refactoring from commit 9e540599 that made FREEZE_PAGE WAL
records use a standard snapshotConflictHorizon style XID cutoff.

No bump in XLOG_PAGE_MAGIC, since the underlying format of affected WAL
records doesn't change.

Author: Peter Geoghegan <pg@bowt.ie>
Reviewed-By: Andres Freund <andres@anarazel.de>
Discussion: https://postgr.es/m/CAH2-Wzm2CQUmViUq7Opgk=McVREHSOorYaAjR1ZpLYkRN7_dPw@mail.gmail.com

1 files changed, 7 insertions, 7 deletions

diff --git a/src/backend/access/heap/pruneheap.c b/src/backend/access/heap/pruneheap.c
index 9f43bbe25f..91c5f5e9ef 100644
--- a/src/backend/access/heap/pruneheap.c
+++ b/src/backend/access/heap/pruneheap.c
@@ -49,7 +49,7 @@ typedef struct
 	bool		old_snap_used;
 
 	TransactionId new_prune_xid;	/* new prune hint value for page */
-	TransactionId latestRemovedXid; /* latest xid to be removed by this prune */
+	TransactionId snapshotConflictHorizon;	/* latest xid removed */
 	int			nredirected;	/* numbers of entries in arrays below */
 	int			ndead;
 	int			nunused;
@@ -295,7 +295,7 @@ heap_page_prune(Relation relation, Buffer buffer,
 	prstate.old_snap_xmin = old_snap_xmin;
 	prstate.old_snap_ts = old_snap_ts;
 	prstate.old_snap_used = false;
-	prstate.latestRemovedXid = InvalidTransactionId;
+	prstate.snapshotConflictHorizon = InvalidTransactionId;
 	prstate.nredirected = prstate.ndead = prstate.nunused = 0;
 	memset(prstate.marked, 0, sizeof(prstate.marked));
 
@@ -418,7 +418,7 @@ heap_page_prune(Relation relation, Buffer buffer,
 			xl_heap_prune xlrec;
 			XLogRecPtr	recptr;
 
-			xlrec.latestRemovedXid = prstate.latestRemovedXid;
+			xlrec.snapshotConflictHorizon = prstate.snapshotConflictHorizon;
 			xlrec.nredirected = prstate.nredirected;
 			xlrec.ndead = prstate.ndead;
 
@@ -636,8 +636,8 @@ heap_prune_chain(Buffer buffer, OffsetNumber rootoffnum, PruneState *prstate)
 				!HeapTupleHeaderIsHotUpdated(htup))
 			{
 				heap_prune_record_unused(prstate, rootoffnum);
-				HeapTupleHeaderAdvanceLatestRemovedXid(htup,
-													   &prstate->latestRemovedXid);
+				HeapTupleHeaderAdvanceConflictHorizon(htup,
+													  &prstate->snapshotConflictHorizon);
 				ndeleted++;
 			}
 
@@ -773,8 +773,8 @@ heap_prune_chain(Buffer buffer, OffsetNumber rootoffnum, PruneState *prstate)
 		if (tupdead)
 		{
 			latestdead = offnum;
-			HeapTupleHeaderAdvanceLatestRemovedXid(htup,
-												   &prstate->latestRemovedXid);
+			HeapTupleHeaderAdvanceConflictHorizon(htup,
+												  &prstate->snapshotConflictHorizon);
 		}
 		else if (!recent_dead)
 			break;