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Re: On-disk bitmap index patch

From: mark(at)mark(dot)mielke(dot)cc
To: Luke Lonergan <llonergan(at)greenplum(dot)com>
Cc: Bruce Momjian <bruce(at)momjian(dot)us>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>,Dann Corbit <DCorbit(at)connx(dot)com>,"Jim C(dot) Nasby" <jnasby(at)pervasive(dot)com>,Jie Zhang <jzhang(at)greenplum(dot)com>,Mark Kirkwood <markir(at)paradise(dot)net(dot)nz>,Josh Berkus <josh(at)agliodbs(dot)com>,Gavin Sherry <swm(at)linuxworld(dot)com(dot)au>, pgsql-hackers(at)postgresql(dot)org
Subject: Re: On-disk bitmap index patch
Date: 2006-07-29 04:26:23
Message-ID: 20060729042622.GA22145@mark.mielke.cc (view raw or flat)
Thread:
Lists: pgsql-hackers
On Fri, Jul 28, 2006 at 02:43:23PM -0700, Luke Lonergan wrote:
> On 7/28/06 1:25 PM, "Bruce Momjian" <bruce(at)momjian(dot)us> wrote:
> > What we don't want to happen is for us to release bitmapped indexes, and
> > find out later that btree is better in all cases.  Then we have to tell
> > people not to use bitmapped indexes until we fix it in the next major
> > releasse.  FYI, that is  basically where we are right now with hash
> > indexes.
> On this thread people have presented results that show clear and irrefutable
> evidence that there are use cases where bitmap indexes outperform Btree for
> many datatypes on realistic problems, including the TPC-H benchmark.

Irrefutable is a little optimistic, don't you think? :-)

There is reason to believe that a bitmap index is useful in some
scenarios. We're not yet clear on what these are, whether they apply
to production use scenarios, or whether b-tree could not be optimized
to be better.

I support you - I want to see these great things for myself.

But irrefutable? Irrefutable is not true. :-)

Cheers,
mark

-- 
mark(at)mielke(dot)cc / markm(at)ncf(dot)ca / markm(at)nortel(dot)com     __________________________
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