From: Heikki Linnakangas <hlinnakangas@vmware.com>
To: Grzegorz Olszewski <grzegorz.olszewski@outlook.com>
To: AI Rumman <rummandba@gmail.com>
Cc: pgsql-performance@postgresql.org <pgsql-performance@postgresql.org>
Subject: Re: Planner doesn't take indexes into account
Date: Wed, 28 May 2014 13:22:43 +0300
Message-ID: <5385B8F3.2000103@vmware.com> (raw)
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On 05/28/2014 12:59 PM, Grzegorz Olszewski wrote:
> random_page_cost = 4.0
> seq_page_cost = 1.0
>
> There is about 500,000 rows and about 500 new rows each business day.
>
> About 96% of rows meet given conditions, that is, count shoud be about 480,000.
When such a large percentage of the rows match, a sequential scan is
indeed a better plan than an index scan. Sequential access is much
faster than random access.
- Heikki
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To: pgsql-performance@postgresql.org
Cc: hlinnakangas@vmware.com, grzegorz.olszewski@outlook.com, rummandba@gmail.com
Subject: Re: Planner doesn't take indexes into account
In-Reply-To: <5385B8F3.2000103@vmware.com>
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