Christophe Pettus <xof@thebuild.com> writes:
> Note that it's waiting for a ShareLock, not an AccessExclusiveLock, thus my question.
> Just to clarify, my very specific question is about "AccessExclusiveLock".
I believe it'll depend on which PG version you're testing. Alvaro whacked
that stuff around in connection with FOR SHARE LOCK and related features.
The short answer is that heavyweight tuple locks can be taken internally
by UPDATE, DELETE, and other row-level operations, and the specifics of
which type of lock any given action takes are implementation details that
can change from time to time.
regards, tom lane