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From: Jeremy Harris <jgh@wizmail.org>
To: pgsql-performance@postgresql.org
Subject: Re: Choice of bitmap scan over index scan
Date: Sun, 10 Jan 2010 14:04:47 +0000
Message-ID: <4B49DE7F.8080808@wizmail.org> (raw)
In-Reply-To: <d4468d971001100428v30236b55nb4cc82d216c7819e@mail.gmail.com>
References: <d4468d971001100428v30236b55nb4cc82d216c7819e@mail.gmail.com>

On 01/10/2010 12:28 PM, Mathieu De Zutter wrote:
>Sort  (cost=481763.31..485634.61 rows=1548520 width=338) (actual time=5423.628..6286.148 rows=1551923 loops=1)
>   Sort Key: event_timestamp
  >  Sort Method:  external merge  Disk: 90488kB
>   ->  Seq Scan on log_event  (cost=0.00..79085.92 rows=1548520 width=338) (actual time=0.022..2195.527 rows=1551923 loops=1)
>         Filter: (event_timestamp > (now() - '1 year'::interval))
> Total runtime: 6407.377 ms

Needing to use an external (on-disk) sort method, when taking
only 90MB, looks odd.

- Jeremy

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