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From: Jim Nasby <[email protected]>
To: [email protected]
Subject: Question about MVCC caveats
Date: Thu, 13 Nov 2025 13:30:44 -0600
Message-ID: <CAMFBP2oW2xRBJZjpjtLJ_hjLM5fMMA7Sv9SigK5XA5XKXpYyWA@mail.gmail.com> (raw)

At [1], the docs state that table rewrite ALTERs result in the relation
appearing empty after the ALTER if another transaction had already taken a
snapshot before the ALTER. A simple test with a repeatable read (or
serializable) transaction confirms this... but is there any other situation
where a snapshot would be taken?

1: https://www.postgresql.org/docs/current/mvcc-caveats.html


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