On Tue, 2022-09-13 at 16:13 +0200, Matthias van de Meent wrote: > On Tue, 13 Sept 2022 at 15:45, Tom Lane <t...@sss.pgh.pa.us> wrote: > > Laurenz Albe <laurenz.a...@cybertec.at> writes: > > > But once they are deleted or updated, even the transaction that created > > > them cannot > > > see them any more, right? > > > > I would not trust that claim very far. The transaction might have active > > snapshots with a command ID between the times of insertion and deletion. > > (Consider a query that is firing triggers as it goes, and the triggers > > are performing new actions that cause the command counter to advance. > > The outer query should not see the results of those actions.) > > I hadn't realized that triggers indeed consume command ids but might > not be visible to the outer query (that might still be running). That > invalidates the "or (e.g.) the existence of another tuple with the > same XID but with a newer CID" claim I made earlier, so thanks for > clarifying.
Yes, that makes sense. Thanks. Yours, Laurenz Albe
