| From: | Patrick B <patrickbakerbr(at)gmail(dot)com> |
|---|---|
| To: | Venkata B Nagothi <nag1010(at)gmail(dot)com> |
| Cc: | pgsql-general <pgsql-general(at)postgresql(dot)org> |
| Subject: | Re: Vacuum Full - Questions |
| Date: | 2016-09-01 00:32:50 |
| Message-ID: | CAJNY3isRfbsavhDox4PAWmbnwhvW9uyP=r93rTGgknJQrBBDHA@mail.gmail.com |
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| Lists: | pgsql-general |
2016-09-01 11:53 GMT+12:00 Venkata B Nagothi <nag1010(at)gmail(dot)com>:
>
> On Thu, Sep 1, 2016 at 8:41 AM, Patrick B <patrickbakerbr(at)gmail(dot)com>
> wrote:
>
>> Hi guys,
>>
>> A dev has ran a VACUUM FULL command into our test database running
>> PostgreSQL 9.5 (I know... goddamn!!!!)...
>>
>> ... after the Vacuum Full, some queries start using SEQ scans instead of
>> indexes...
>>
>> Does that happen because of the size of the table? The table that I'm
>> referring to is 150MB big after the vacuum (Before was 1G)...
>>
>
> Yes, it is possible that sequential scans after vacuum full are cheaper
> than Index scans before vacuum full ? do you see improvement in query
> response times ?
> How does the cost differ ?
>
> Regards,
> Venkata B N
>
> Fujitsu Australia
>
Well... the response time was worst than when using index.. that's very
weird... I've re-created the indexes now a ran ANALYZE and the query is
using again the index.. just wanted understand what happened...
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