Touch global snapshots csn->xmin map only when track_global_snapshots.

arssher · arssher · commit 9b8e7c34a0ff · 2018-10-11T16:29:36.000+03:00
Actually we should allow this -- it might make sense for hot standby.

(cherry picked from commit 109b20b09e3b7e10015ffa13b7b8cd71345ddfea)
diff --git a/src/backend/access/transam/global_snapshot.c b/src/backend/access/transam/global_snapshot.c
@@ -181,7 +181,8 @@ GlobalSnapshotStartup(TransactionId oldestActiveXID)
 	 * Run only if we have initialized shared memory and gsXidMap
 	 * is enabled.
 	 */
-	if (IsNormalProcessingMode() && global_snapshot_defer_time > 0)
+	if (IsNormalProcessingMode() && track_global_snapshots &&
+		global_snapshot_defer_time > 0)
 	{
 		int i;
 
diff --git a/src/backend/storage/ipc/procarray.c b/src/backend/storage/ipc/procarray.c
@@ -1847,7 +1847,8 @@ GetSnapshotData(Snapshot snapshot)
 	snapshot->imported_global_csn = false;
 	snapshot->global_csn = global_csn;
 	/* if (global_snapshot_defer_time > 0 && IsNormalProcessingMode()) */
-	if (global_snapshot_defer_time > 0 && IsUnderPostmaster)
+	if (track_global_snapshots && global_snapshot_defer_time > 0 &&
+		IsUnderPostmaster)
 		GlobalSnapshotMapXmin(snapshot->global_csn);
 
 	return snapshot;

Original file line number	Diff line number	Diff line change
`@@ -181,7 +181,8 @@ GlobalSnapshotStartup(TransactionId oldestActiveXID)`
`181`	`181`	`* Run only if we have initialized shared memory and gsXidMap`
`182`	`182`	`* is enabled.`
`183`	`183`	`*/`
`184`		`- if (IsNormalProcessingMode() && global_snapshot_defer_time > 0)`
	`184`	`+ if (IsNormalProcessingMode() && track_global_snapshots &&`
	`185`	`+ global_snapshot_defer_time > 0)`
`185`	`186`	`{`
`186`	`187`	`int i;`
`187`	`188`