Message-ID: <4ECD9E19.8080303@catalyst.net.nz>
Date: Thu, 24 Nov 2011 14:30:01 +1300
From: Mark Kirkwood <mark.kirkwood@catalyst.net.nz>
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To: Gary Warner <gar@cis.uab.edu>
CC: pgsql-performance@postgresql.org
Subject: Re: Seq Scan used instead of Index Scan
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Can you post your non-default postgresql.conf settings? (I'd hazard a 
guess that you have effective_cache_size set to the default 128MB).

Best wishes

Mark

On 24/11/11 11:24, Gary Warner wrote:
> Very Fast Version:
>
> Recently my database stopped respecting one of my indexes, which took a query that should run in "subsecond response time" and turning it into something that with small data sets runs in the 7-10 minute range and with large data sets runs in the 30 minute - eternity range.
>
> Explain Analyze tells me that what used to be an Index Scan has become a Seq Scan, doing a full table scan through 140 million records.
>
> Any thoughts on why that happens?
>