Re: Bitmap indexes - Mailing list pgsql-performance

From Tom Lane
Subject Re: Bitmap indexes
Date
Msg-id 2472.1106928826@sss.pgh.pa.us
Whole thread Raw
In response to Bitmap indexes  (Alex Turner <armtuk@gmail.com>)
Responses Re: Bitmap indexes  (PFC <lists@boutiquenumerique.com>)
List pgsql-performance
Alex Turner <armtuk@gmail.com> writes:
> I was wondering about index types.  Oracle has an index type called a
> 'bitmap' index.

There's a great deal about this in the list archives (probably more in
pgsql-hackers than in -performance).  Most of the current interest has
to do with building in-memory bitmaps on the fly, as a way of decoupling
index and heap scan processing.  Which is not quite what you're talking
about but should be pretty effective for low-cardinality cases.  In
particular it'd allow AND and OR combination of multiple indexes, which
we do poorly or not at all at the moment.

            regards, tom lane

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