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 <u...@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: u...@thetaphi.de > > > -----Original Message----- > > From: Otis Gospodnetic [mailto:otis_gospodne...@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-unsubscr...@lucene.apache.org > > For additional commands, e-mail: java-dev-h...@lucene.apache.org > > > > --------------------------------------------------------------------- > To unsubscribe, e-mail: java-dev-unsubscr...@lucene.apache.org > For additional commands, e-mail: java-dev-h...@lucene.apache.org --------------------------------------------------------------------- To unsubscribe, e-mail: java-dev-unsubscr...@lucene.apache.org For additional commands, e-mail: java-dev-h...@lucene.apache.org
