| From: | Don Seiler <don(at)seiler(dot)us> |
|---|---|
| To: | twoflower <standa(dot)kurik(at)gmail(dot)com> |
| Cc: | Postgres General <pgsql-general(at)postgresql(dot)org> |
| Subject: | Re: Postgres 11 chooses seq scan instead of index-only scan |
| Date: | 2019-01-24 15:06:14 |
| Message-ID: | CAHJZqBBK_dMM6FAxb59nEaWNn_fk-i9_em4kQ6svFwje+K4DXw@mail.gmail.com |
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| Lists: | pgsql-general |
On Thu, Jan 24, 2019 at 9:01 AM twoflower <standa(dot)kurik(at)gmail(dot)com> wrote:
> Yes! That was it, after running VACUUM TABLE history_translation, the
> query is now executed using index-only scan.
>
> I was under the impression that ANALYZE TABLE history_translation is
> enough, but it is not.
>
Only a VACUUM will update the visibility map.
https://www.postgresql.org/docs/current/storage-vm.html
I used to think the same, that ANALYZE was enough, coming from an Oracle
background. I learned later that the visibility map isn't just used to
determine what to vacuum, but it is used by the optimizer/planner when
evaluating execution plans.
--
Don Seiler
www.seiler.us
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