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Re: bitmap indexes - performance

From: Bruce Momjian <bruce(at)momjian(dot)us>
To: Leonardo F <m_lists(at)yahoo(dot)it>
Cc: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Robert Haas <robertmhaas(at)gmail(dot)com>, pgsql-hackers(at)postgresql(dot)org
Subject: Re: bitmap indexes - performance
Date: 2010-07-02 01:31:32
Message-ID: 201007020131.o621VWK08371@momjian.us (view raw or flat)
Thread:
Lists: pgsql-hackers
Leonardo F wrote:
> I'm trying to find more docs that explain the "improvements" of
> bitmap indexes in other products... but most of what I've found
> talks about bitmapAND/OR.... which is something that is very
> cool, but that postgres already does even with btree indexes...
> or index creation time/size, which are, for the moment, the only
> things that I'm pretty confident the patch would actually provide.

I think a real limitation of on-disk bitmap indexes is that they are
only feable for low cardinality columns, while btree handles all column
types.

-- 
  Bruce Momjian  <bruce(at)momjian(dot)us>        http://momjian.us
  EnterpriseDB                             http://enterprisedb.com

  + None of us is going to be here forever. +

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