| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | "A(dot) Kretschmer" <andreas(dot)kretschmer(at)schollglas(dot)com> |
| Cc: | pgsql-sql(at)postgresql(dot)org |
| Subject: | Re: slow query |
| Date: | 2007-04-05 05:27:25 |
| Message-ID: | 19157.1175750845@sss.pgh.pa.us |
| Views: | Raw Message | Whole Thread | Download mbox | Resend email |
| Thread: | |
| Lists: | pgsql-sql |
"A. Kretschmer" <andreas(dot)kretschmer(at)schollglas(dot)com> writes:
> am Wed, dem 04.04.2007, um 23:17:54 -0400 mailte Sumeet folgendes:
>> sm=> explain analyze select * from ma limit 10;
>> QUERY
>> PLAN
>> -------------------------------------------------------------------------------------------------------------------------------------
>> Limit (cost=0.00..0.45 rows=10 width=76) (actual time=21985.292..22204.340
>> rows=10 loops=1)
>> -> Seq Scan on ma (cost=0.00..2181956.92 rows=48235392 width=76) (actual
>> time=21985.285..22204.308 rows=10 loops=1)
>> Total runtime: 22204.476 ms
>> (3 rows)
> which version?
I'm betting the problem is poor vacuuming practice leading to lots of
dead space. There's no way it takes 22 sec to read 10 rows if the
table is reasonably dense.
regards, tom lane
| From | Date | Subject | |
|---|---|---|---|
| Next Message | A. Kretschmer | 2007-04-05 05:36:38 | Re: slow query |
| Previous Message | Tom Lane | 2007-04-05 05:23:50 | Re: Very slow DELETE on 4000 rows of 55000 row table |