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Re: seq scan issue...

From: "Jeffrey Baker" <jwbaker(at)gmail(dot)com>
To: "kevin kempter" <kevin(at)kevinkempterllc(dot)com>, pgsql-performance(at)postgresql(dot)org
Subject: Re: seq scan issue...
Date: 2008-04-17 18:30:15
Message-ID: fd145f7d0804171130g6549ace3u14876385420f8c11@mail.gmail.com (view raw or flat)
Thread:
Lists: pgsql-performance
On Thu, Apr 17, 2008 at 11:24 AM, kevin kempter
<kevin(at)kevinkempterllc(dot)com> wrote:
> Hi List;
>
>  I have a large tble (playback_device) with 6million rows in it. The
> aff_id_tmp1 table has 600,000 rows.
>  - why am I still getting a seq scan ?
>

You're selecting almost all the rows in the product of aff_id_tmp1 *
playback_fragment.  A sequential scan will be far faster than an index
scan.  You can prove this to yourself using 'set enable_seqscan to
false' and running the query again.  It should be much slower.

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