Re: seq-scan or index-scan - Mailing list pgsql-general

From Andreas Kretschmer
Subject Re: seq-scan or index-scan
Date
Msg-id 20120705061600.GA7818@tux
Whole thread Raw
In response to Re: seq-scan or index-scan  (Tom Lane <tgl@sss.pgh.pa.us>)
List pgsql-general
Tom Lane <tgl@sss.pgh.pa.us> wrote:

> Andreas Kretschmer <akretschmer@spamfence.net> writes:
> > production=*# explain analyse select * from boxes;
> >                                                   QUERY PLAN
> > ---------------------------------------------------------------------------------------------------------------
> >  Seq Scan on boxes  (cost=0.00..990783.99 rows=6499 width=581) (actual time=6.514..4588.136 rows=3060 loops=1)
> >  Total runtime: 4588.729 ms
> > (2 rows)
>
> That cost estimate seems pretty dang large for a table with only 6500
> rows.  I suspect this table is horribly bloated, and the indexscan
> manages to win because it's not visiting pages that contain only dead

You're right as always ;-)

A LOT of updates and dead rows and the table is bloated.
(some rows contains more than 1MByte of TEXT and some rows updated once
per second or so)


> rows.  Try VACUUM FULL, and if that makes things saner, re-examine
> your autovacuum settings.

I can't run a VACUUM FULL because of the workload, but i have decrease
the fillfactor.


Andreas
--
Really, I'm not out to destroy Microsoft. That will just be a completely
unintentional side effect.                              (Linus Torvalds)
"If I was god, I would recompile penguin with --enable-fly."   (unknown)
Kaufbach, Saxony, Germany, Europe.              N 51.05082°, E 13.56889°

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