| From: | "A(dot) Kretschmer" <andreas(dot)kretschmer(at)schollglas(dot)com> |
|---|---|
| To: | pgsql-performance(at)postgresql(dot)org |
| Subject: | Re: Regarding Bitmap Scan |
| Date: | 2006-10-17 11:45:11 |
| Message-ID: | 20061017114511.GD19268@a-kretschmer.de |
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| Lists: | pgsql-performance |
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
Kontakt: Heynitz: 035242/47215, D1: 0160/7141639 (mehr: -> Header)
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