Re: Question about Bitmap Heap Scan/BitmapAnd - Mailing list pgsql-performance

From Alvaro Herrera
Subject Re: Question about Bitmap Heap Scan/BitmapAnd
Date
Msg-id 20070215162733.GO4682@alvh.no-ip.org
Whole thread Raw
In response to Re: Question about Bitmap Heap Scan/BitmapAnd  ("Guillaume Smet" <guillaume.smet@gmail.com>)
Responses Re: Question about Bitmap Heap Scan/BitmapAnd
List 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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