91120734db
If we had not been holding buffer pin continuously since the tuple was initially fetched by the UPDATE or DELETE query, it would be possible for VACUUM or a page-prune operation to move the tuple while we're trying to copy it. This would result in a garbage "old" tuple value being passed to an AFTER ROW UPDATE or AFTER ROW DELETE trigger. The preconditions for this are somewhat improbable, and the timing constraints are very tight; so it's not so surprising that this hasn't been reported from the field, even though the bug has been there a long time. Problem found by Andres Freund. Back-patch to all active branches.
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