From: A. Kretschmer <andreas.kretschmer@schollglas.com>
To: pgsql-performance@postgresql.org
Subject: Re: Regarding Bitmap Scan
Date: Tue, 17 Oct 2006 13:45:11 +0200
Message-ID: <20061017114511.GD19268@a-kretschmer.de> (raw)
In-Reply-To: <9f2e40a90610170439n4b670c23ld586e4f0840e943@mail.gmail.com>
References: <9f2e40a90610170439n4b670c23ld586e4f0840e943@mail.gmail.com>
am Tue, dem 17.10.2006, um 17:09:29 +0530 mailte soni de folgendes:
> I didn't understand the "Bitmap Scan" and the sentence "indexes will be
> dynamically converted to bitmaps in memory". What does mean by "Bitmap Scan" in
> database?
For instance, you have a large table with 5 indexes on this and a query
that checks conditions on this 5 columns.
PG is now able to combine this 5 indexes and performs only 1 bitmap
index scan on this table, and not 5 independet nested bitmap scans.
A realy very great performance-boost!
HTH, Andreas
--
Andreas Kretschmer
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To: pgsql-performance@postgresql.org
Cc: andreas.kretschmer@schollglas.com
Subject: Re: Regarding Bitmap Scan
In-Reply-To: <20061017114511.GD19268@a-kretschmer.de>
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