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Re: Question about Bitmap Heap Scan/BitmapAnd

From: Alvaro Herrera <alvherre(at)commandprompt(dot)com>
To: Guillaume Smet <guillaume(dot)smet(at)gmail(dot)com>
Cc: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, pgsql-performance(at)postgresql(dot)org
Subject: Re: Question about Bitmap Heap Scan/BitmapAnd
Date: 2007-02-15 16:27:33
Message-ID: 20070215162733.GO4682@alvh.no-ip.org (view raw or flat)
Thread:
Lists: pgsql-performance
Guillaume Smet escribió:

> I'm still working on my proximity query, testing PostGIS now. I
> noticed an issue with a gist index on a point which seems related to
> my previous question.
> 
> I have the following in my plan:
> ->  Bitmap Heap Scan on lieu l  (cost=13.37..1555.69 rows=844
> width=118) (actual time=3.672..39.497 rows=1509 loops=1)
>      Filter: (((dfinvalidlieu IS NULL) OR (dfinvalidlieu >= now()))
> AND (wgslat IS NOT NULL) AND (wgslon IS NOT NULL) AND (wgslat <>
> 41.89103400) AND (wgslon <> 12.49244400) AND (earthpoint &&
> '0103000020777F0000010000000500000000000040019B334100000020D1D8514100000040019B334100000040ADDE51410000006071B2334100000040ADDE51410000006071B2334100000020D1D8514100000040019B334100000020D1D85141'::geometry)
> AND (numlieu <> 49187))
>       ->  Bitmap Index Scan on idx_lieu_earthpoint  (cost=0.00..13.37
> rows=1249 width=0) (actual time=2.844..2.844 rows=1510 loops=1)
>             Index Cond: (earthpoint &&
> '0103000020777F0000010000000500000000000040019B334100000020D1D8514100000040019B334100000040ADDE51410000006071B2334100000040ADDE51410000006071B2334100000020D1D8514100000040019B334100000020D1D85141'::geometry)
> 
> Is it normal I have no recheck cond and the index cond of Bitmap Index
> Scan is in the filter? Is it also a consequence of the code you
> pointed?

It is in the filter, is it not?  Having a recheck would be redundant.

-- 
Alvaro Herrera                                http://www.CommandPrompt.com/
The PostgreSQL Company - Command Prompt, Inc.

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Next:From: Tom LaneDate: 2007-02-15 16:34:49
Subject: Re: Question about Bitmap Heap Scan/BitmapAnd
Previous:From: Guillaume SmetDate: 2007-02-15 16:13:34
Subject: Re: Proximity query with GIST and row estimation

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