lucene-dev mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Otis Gospodnetic <otis_gospodne...@yahoo.com>
Subject Re: Bitmap index
Date Fri, 27 Feb 2009 21:46:00 GMT

OK, so that bit about filters, OpenBitSet and friends was my feeling/understanding, too. 
That sort of matches what that Wikipedia page describes as in-memory usage of bitmaps a la
PostgreSQL.  The reason I mentioned Solr is because I was thinking of low-cardinality fields,
perhaps the same ones that people tend to use for faceting.

Otis



----- Original Message ----
> From: Uwe Schindler <uwe@thetaphi.de>
> To: java-dev@lucene.apache.org
> Sent: Friday, February 27, 2009 4:37:19 PM
> Subject: RE: Bitmap index
> 
> 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
> > 
> > ---------------------------------------------------------------------
> > To unsubscribe, e-mail: java-dev-unsubscribe@lucene.apache.org
> > For additional commands, e-mail: java-dev-help@lucene.apache.org
> 
> 
> 
> ---------------------------------------------------------------------
> To unsubscribe, e-mail: java-dev-unsubscribe@lucene.apache.org
> For additional commands, e-mail: java-dev-help@lucene.apache.org


---------------------------------------------------------------------
To unsubscribe, e-mail: java-dev-unsubscribe@lucene.apache.org
For additional commands, e-mail: java-dev-help@lucene.apache.org


Mime
View raw message