Subject: [PATCH 2/2] What about just ignoring the xacts if they're still running?

From: Álvaro Herrera <[email-masked]>
Date: Fri, 20 Mar 2026 15:58:05 +0100

---
 src/backend/replication/logical/snapbuild.c | 37 +++++----------------
 1 file changed, 8 insertions(+), 29 deletions(-)

diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index d7ea098cb37..2a4581b75a6 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -402,38 +402,17 @@ SnapBuildBuildSnapshot(SnapBuild *builder)
 	snapshot->xmin = builder->xmin;
 	snapshot->xmax = builder->xmax;
 
-	/*
-	 * Although it's very unlikely, it's possible that a commit WAL record was
-	 * decoded but CLOG is not aware of the commit yet. Should the CLOG update
-	 * be delayed even more, visibility checks that use this snapshot could
-	 * work incorrectly. Therefore we check the CLOG status here.
-	 */
-	for (int i = 0; i < builder->committed.xcnt; i++)
-	{
-		for (;;)
-		{
-			if (TransactionIdDidCommit(builder->committed.xip[i]))
-				break;
-			else
-			{
-				(void) WaitLatch(MyLatch,
-								 WL_LATCH_SET | WL_TIMEOUT |
-								 WL_EXIT_ON_PM_DEATH,
-								 10L,
-								 WAIT_EVENT_SNAPBUILD_CLOG);
-				ResetLatch(MyLatch);
-			}
-			CHECK_FOR_INTERRUPTS();
-		}
-	}
-
 	/* store all transactions to be treated as committed by this snapshot */
 	snapshot->xip =
 		(TransactionId *) ((char *) snapshot + sizeof(SnapshotData));
-	snapshot->xcnt = builder->committed.xcnt;
-	memcpy(snapshot->xip,
-		   builder->committed.xip,
-		   builder->committed.xcnt * sizeof(TransactionId));
+
+	for (int i = 0; i < builder->committed.xcnt; i++)
+	{
+		if (!TransactionIdIsInProgress(builder->committed.xip[i]))
+		{
+			snapshot->xip[snapshot->xcnt++] = builder->committed.xip[i];
+		}
+	}
 
 	/* sort so we can bsearch() */
 	qsort(snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator);
-- 
2.47.3

--obdbyrpgpb3edptv--