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Re: Bitmap indexes

From: PFC <lists(at)boutiquenumerique(dot)com>
To: alex(at)neteconomist(dot)com,"PostgreSQL Perfomance" <pgsql-performance(at)postgresql(dot)org>
Subject: Re: Bitmap indexes
Date: 2005-01-28 16:04:48
Message-ID: opslblmagoth1vuj@musicbox (view raw or flat)
Thread:
Lists: pgsql-performance
	contrib/intarray has an index type which could be what you need.


> I was wondering about index types.  Oracle has an index type called a
> 'bitmap' index.  They describe this as an index for low cardinality
> fields, where only the cardinal values are indexed in a b-tree, and
> then it uses a bitmap below that to describe rows.  They say that this
> type of index is very fast when combined with queries that used the
> indexed row in 'AND' clauses in a sql statement as the index can
> 'mask' the results very fast.  I have not been able to benchmark the
> actual effectiveness of this kind of index, but I was wondering if
> anyone has had experience with this an believes it might be a useful
> feature for postgres?
>
> Yes I have a vested interest in this because alot of my searches are
> masked against low cardinality fields 'Y' or 'N' type things where
> this could potentialy benefit me...
>
> Alex Turner
> NetEconomist
>
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