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From Otis Gospodnetic <otis_gospodne...@yahoo.com>
Subject Re: Bitmap index
Date Fri, 27 Feb 2009 21:48:02 GMT

So that would require Lucene to dynamically/periodically check field values and their frequencies
and switch from a regular inverted index to a bitmap index or just create an additional bitmap
index for those fields and their values?

Otis



----- Original Message ----
> From: Michael McCandless <lucene@mikemccandless.com>
> To: java-dev@lucene.apache.org
> Sent: Friday, February 27, 2009 4:41:32 PM
> Subject: Re: Bitmap index
> 
> 
> I think with column stride fields we should use Bitmap Index to represent fields 
> that have few values across many docs.
> 
> Mike
> 
> Uwe Schindler wrote:
> 
> > In my opinion, we currently use some type of bitmap index with our filters.
> > OpenBitSet and SortedVIntList used in filters can be seen as bitmap indexes
> > specifying if a document is a hit of the filter or not. Maybe we can use the
> > compression technology mentioned in this Wikipedia article to further
> > optimize filters and their DocIdSetIterators.
> > 
> > In my opinion, the real use of bitmap indexes is data warehousing, when
> > low-cardinality-columns are used. We are using Sybase IQ (a column oriented
> > database) that has heavy usage of bitmap indexes (a variation of them are
> > called LF - low-fast indexes there).
> > 
> > Uwe
> > 
> > -----
> > Uwe Schindler
> > H.-H.-Meier-Allee 63, D-28213 Bremen
> > http://www.thetaphi.de
> > eMail: uwe@thetaphi.de
> > 
> >> -----Original Message-----
> >> From: Otis Gospodnetic [mailto:otis_gospodnetic@yahoo.com]
> >> Sent: Friday, February 27, 2009 9:33 PM
> >> To: java-dev@lucene.apache.org
> >> Subject: Bitmap index
> >> 
> >> 
> >> Hi,
> >> 
> >> I've had http://en.wikipedia.org/wiki/Bitmap_index open in my browser for
> >> weeks, thinking I'd bring it up here -- would a bitmap index make sense
> >> anywhere in Lucene (or perhaps Solr)?
> >> 
> >> Otis
> >> 
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> > 
> > 
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> 
> 
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