| From: | Kevin Grittner <kgrittn(at)ymail(dot)com> |
|---|---|
| To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Cc: | Carlos Henrique Reimer <carlos(dot)reimer(at)opendb(dot)com(dot)br>, "pgsql-general(at)postgresql(dot)org" <pgsql-general(at)postgresql(dot)org> |
| Subject: | Re: Runtime variations during day |
| Date: | 2013-02-13 22:17:45 |
| Message-ID: | 1360793865.10173.YahooMailNeo@web162904.mail.bf1.yahoo.com |
| Views: | Raw Message | Whole Thread | Download mbox | Resend email |
| Thread: | |
| Lists: | pgsql-general |
Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> I'm wondering about cache effects, ie memory already contains
> desired pages in the morning (perhaps as a side-effect of queries
> run overnight) and not so much by the evening. If so it's not
> clear that additional VACUUM activity would make things better.
>
> But in any case it's hard to diagnose this without EXPLAIN
> ANALYZE output.
He did show EXPLAIN OUTPUT results, which showed an index scan in
the morning and a seqscan in the evening. He also mentioned that
he doubted cache effects amounted to much because the database was
40GB and the machine has 64GB.
--
Kevin Grittner
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company
| From | Date | Subject | |
|---|---|---|---|
| Next Message | René Romero Benavides | 2013-02-13 22:20:38 | Re: Failing backups, canceling statement due to conflict with recovery |
| Previous Message | Tom Lane | 2013-02-13 21:53:57 | Re: Runtime variations during day |