| From: | Ken Marshall <ktm(at)rice(dot)edu> |
|---|---|
| To: | pgsql-general(at)lists(dot)postgresql(dot)org |
| Subject: | Re: Disk wait problem... |
| Date: | 2023-10-23 20:09:16 |
| Message-ID: | ZTbS7H0czxr7rSlg@aart.rice.edu |
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| Thread: | |
| Lists: | pgsql-general |
> Hi,
>
> I have a 1.6TB database with over 330 tables on a 4TB NVMe SSD. All
> tables are static (no updates); most in 8M and 33M row sizes. Queries have
> been great, until recently.
> Also attached is the relevant system journal entries for one query that
> took 2 seconds and two more that took 62 and 52 seconds... Unlike the
> above, these had 3 processes in disk-wait -- see attached screenshot...
>
> I just stopped PG, updated the full backup which was done overnight (so
> the update took about a second), restarted PG and the problem persists...
>
> Any suggestions where to look next?
>
> Thanks,
> Pierre
Hi Pierre,
I have seen this type of behavior when parallel queries were enabled and
PostgreSQL decided that a parallel sequential scan query was the fastest
option. Try disabling them and see if that helps.
Regards,
Ken
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