| From: | Laurenz Albe <laurenz(dot)albe(at)cybertec(dot)at> |
|---|---|
| To: | Lars Aksel Opsahl <Lars(dot)Opsahl(at)nibio(dot)no>, "pgsql-performance(at)lists(dot)postgresql(dot)org" <pgsql-performance(at)lists(dot)postgresql(dot)org> |
| Subject: | Re: "not related" code blocks for removal of dead rows when using vacuum and this kills the performance |
| Date: | 2024-02-20 07:29:14 |
| Message-ID: | 82d75b5687ab9e3dc2a5040f10a227bd1cebf066.camel@cybertec.at |
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| Lists: | pgsql-performance |
On Tue, 2024-02-20 at 05:46 +0000, Lars Aksel Opsahl wrote:
> If this is expected behavior it means that any user on the database that writes
> a long running sql that does not even insert any data can kill performance for
> any other user in the database.
Yes, that is the case. A long running query will hold a snapshot, and no data
visible in that snapshot can be deleted.
That can cause bloat, which can impact performance.
> So applications like QGIS who seems to keep open connections for a while can
> then also kill the performance for any other user in the data.
No, that is not a problem. Keeping *connections* open is a good thing. It is
keeping data modifying transactions, cursors or long-running queries open
that constitutes a problem.
Yours,
Laurenz Albe
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