Re: BUG #17330: EXPLAIN hangs and very long query plans

Hi

pá 10. 12. 2021 v 10:25 odesílatel Strahinja Kustudić <
strahinjak(at)nordeus(dot)com> napsal:

> On Fri, Dec 10, 2021 at 2:36 AM Peter Geoghegan <pg(at)bowt(dot)ie> wrote:
>
>> Sounds like a problem with get_actual_variable_range(), which can scan
>> indexes at plan time to determine minimum or maximum values.
>>
>> This actually has been improved quite a bit since Postgres 10. So as
>> Jeff said, seems like you might benefit from upgrading to a newer
>> major version. v11 has improved things in this exact area.
>>
>
> On my Docker instance when I execute EXPLAIN it starts reading a lot of
> data. The indexes of the biggest table the query reads are 50GB, so my
> guess is that it reads those indexes.
>
> I allowed EXPLAIN in Docker to finish and it took almost 500 seconds and
> it was reading data all the time. After I reindexed the biggest table,
> EXPLAIN finished instantly. Can the index corruption cause this?
>

The index can be bloated.

> Note that this started happening in production after we deleted a few
> million rows from the biggest table.
>

it is maybe same issue

https://www.postgresql.org/message-id/9ADAF560-F331-4AF8-A28A-F005070C3187%40yandex.ru

Regards

Pavel

> Regards,
> Strahinja
>