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Laurent,
Thanks for the advice about REPEATABLE READ isolation level!
Seb
From: Laurenz Albe <laurenz.albe@xxxxxxxxxxx>
Sent: Wednesday, March 29, 2023 1:08 PM To: Kirk Wolak <wolakk@xxxxxxxxx>; Sebastien Flaesch <sebastien.flaesch@xxxxxxx> Cc: Geoff Winkless <pgsqladmin@xxxxxxxx>; pgsql-general <pgsql-general@xxxxxxxxxxxxxxxxxxxx> Subject: Re: Using CTID system column as a "temporary" primary key EXTERNAL: Do not click links or open attachments if you do not recognize the sender.
On Tue, 2023-03-28 at 14:24 -0400, Kirk Wolak wrote: > > I cringe at the thought of using CTID. And while it's probably "safe enough" > inside a single transaction. I doubt that there is much "testing" of this concept. It is safe to assume that the CTID is stable within a single transaction only if you use REPEATABLE READ or better transaction isolation level. With READ COMMITTED, you see updated rows (and consequently changed CTID) within a single transaction. And if you use SELECT ... FOR UPDATE, you could even see a changed CTID within a single statement. So don't use CTID to identify rows unless you use REPEATABLE READ or better. Yours, Laurenz Albe |
