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commit    2ef048855fdc770302a2c5897c6bbeef8af4ad62
Author:   Heikki Linnakangas <heikki.linnakangas@iki.fi>
Date:     Mon Mar 10 15:07:38 2025 +0000

    Fix snapshot used in logical replication index lookup
    
    The function calls GetLatestSnapshot() to acquire a fresh snapshot,
    makes it active, and was meant to pass it to table_tuple_lock(), but
    instead called GetLatestSnapshot() again to acquire yet another
    snapshot. It was harmless because the heap AM and all other known
    table AMs ignore the 'snapshot' argument anyway, but let's be tidy.
    
    In the long run, this perhaps should be redesigned so that snapshot
    was not needed in the first place. The table AM API uses TID +
    snapshot as the unique identifier for the row version, which is
    questionable when the row came from an index scan with a Dirty
    snapshot. You might lock a different row version when you use a
    different snapshot in the table_tuple_lock() call (a fresh MVCC
    snapshot) than in the index scan (DirtySnapshot). However, in the heap
    AM and other AMs where the TID alone identifies the row version, it
    doesn't matter. So for now, just fix the obvious albeit harmless bug.
    
    This has been wrong ever since the table AM API was introduced in
    commit 5db6df0c01, so backpatch to all supported versions.
    
    Discussion: https://www.postgresql.org/message-id/83d243d6-ad8d-4307-8b51-2ee5844f6230@iki.fi
    Backpatch-through: 13


 src/backend/executor/execReplication.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/backend/executor/execReplication.c b/src/backend/executor/execReplication.c
index 8134dea406f..d3bd7974120 100644
--- a/src/backend/executor/execReplication.c
+++ b/src/backend/executor/execReplication.c
@@ -175,7 +175,7 @@ retry:
 
 		PushActiveSnapshot(GetLatestSnapshot());
 
-		res = table_tuple_lock(rel, &(outslot->tts_tid), GetLatestSnapshot(),
+		res = table_tuple_lock(rel, &(outslot->tts_tid), GetActiveSnapshot(),
 							   outslot,
 							   GetCurrentCommandId(false),
 							   lockmode,


[parent: e7d29d1fac82]