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Re: Optimizing Bitmap Heap Scan.

From: Robert Haas <robertmhaas(at)gmail(dot)com>
To: Lennin Caro <lennin(dot)caro(at)yahoo(dot)com>
Cc: Grzegorz Jaśkiewicz <gryzman(at)gmail(dot)com>, niraj patel <npatel(at)gridsolv(dot)com>, pgsql-performance(at)postgresql(dot)org
Subject: Re: Optimizing Bitmap Heap Scan.
Date: 2009-12-08 18:30:32
Message-ID: 603c8f070912081030s3e7ba2fay6164de15529cb4e4@mail.gmail.com (view raw or flat)
Thread:
Lists: pgsql-performance
2009/12/8 Lennin Caro <lennin(dot)caro(at)yahoo(dot)com>
>
> From: niraj patel <npatel(at)gridsolv(dot)com>
>
> Subject: Re: [PERFORM] Optimizing Bitmap Heap Scan.
> To: "Grzegorz Jaśkiewicz" <gryzman(at)gmail(dot)com>
> Cc: pgsql-performance(at)postgresql(dot)org
> Date: Tuesday, December 8, 2009, 1:50 PM
>
> Hi gryzman,
>
> I have run vacuum full analyze on the cmrules tables. The version of pstgres is 8.2.13. How should I change stats to 100 ?
>
> Thanks
> ________________________________
> From: Grzegorz Jaśkiewicz <gryzman(at)gmail(dot)com>
> To: niraj patel <npatel(at)gridsolv(dot)com>
> Cc: pgsql-performance(at)postgresql(dot)org
> Sent: Tue, 8 December, 2009 7:12:49 PM
> Subject: Re: [PERFORM] Optimizing Bitmap Heap Scan.
>
> it looks like it might choose wrong plan, cos it gets the stats wrong.
> Try increasing number of stats to 100.
> Btw, what version it is ?
>
>
> in psql
> mydb=# set default_statistics_target = 100;

That's only going to affect the current session.  To change it
permanently, edit postgresql.conf and do pg_ctl reload.

...Robert

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