Re: Question about MVCC caveats - Mailing list pgsql-general

From Laurenz Albe
Subject Re: Question about MVCC caveats
Date
Msg-id 224564d6e38cef32d7b19e90bb15080dbaa79ea0.camel@cybertec.at
Whole thread Raw
In response to Question about MVCC caveats  (Jim Nasby <jnasby@upgrade.com>)
List pgsql-general
On Thu, 2025-11-13 at 13:30 -0600, Jim Nasby wrote:
> 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?

Snapshots are taken at the start of a statement (or, with REPEATABLE READ and
SERIALIZABLE) at the beginning of the first statement in the transaction.

What do you mean with an "other" situation?

Yours,
Laurenz Albe



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