| From: | Shira Bezalel <shira(at)sfei(dot)org> |
|---|---|
| To: | Tomas Vondra <tomas(dot)vondra(at)2ndquadrant(dot)com> |
| Cc: | Michael Lewis <mlewis(at)entrata(dot)com>, Justin Pryzby <pryzby(at)telsasoft(dot)com>, postgres performance list <pgsql-performance(at)postgresql(dot)org> |
| Subject: | Re: Seeking reason behind performance gain in 12 with HashAggregate |
| Date: | 2020-01-13 21:45:55 |
| Message-ID: | CAE0KEwEyMhS85CcUJyom6QQ4VtSn6bwxiz-VoBpRe4DWw-12CQ@mail.gmail.com |
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| Lists: | pgsql-performance |
Thanks Tomas. I ran a vacuum full on the 9.6 table -- still no difference
in the query plan. The shared buffers hit went up slightly to 36069.
Shira
On Mon, Jan 13, 2020 at 1:12 PM Tomas Vondra <tomas(dot)vondra(at)2ndquadrant(dot)com>
wrote:
> On Mon, Jan 13, 2020 at 12:44:14PM -0800, Shira Bezalel wrote:
> >Hi Michael,
> >
> >I appreciate your question. I ran a vacuum analyze on the 9.6 table and it
> >yielded no difference. Same number of buffers were read, same query plan.
> >
>
> VACUUM ANALYZE won't shrink the table - the number of buffers will be
> exactly the same. You need to do VACUUM FULL, but be careful as that
> acquires exclusive lock on the table.
>
>
> regards
>
> --
> Tomas Vondra http://www.2ndQuadrant.com
> PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
>
--
Shira Bezalel
Database Administrator & Desktop Support Manager
San Francisco Estuary Institute
www.sfei.org
Ph: 510-746-7304
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