From: Martin Smith Subject: Re: Shrinking an index?? Date: 1997/04/01 Message-ID: <3341E7CB.1E4A@erols.com>#1/1 References: <332d9ec6.755998@news.cac.psu.edu> <5gn21m$a0q@camel4.mindspring.com> <333e7915.1569004@news.centroin.com.br> Organization: Erol's Internet Services X-Received-On: 1 Apr 1997 23:59:41 GMT Newsgroups: comp.databases.oracle.server,comp.databases.oracle.misc The docs say where there's a 1,000:1 ratio of rows to distinct values. So for a million-row table, "low" cardinality would be anything under 10,000 values. We have an application with about 10 keys (dimensions); ALL BUT ONE of these it bit-mapped. Works like wildfire and saves mucho storage. Plus you don't have to pre-select the index combinations you will use. Seems like a huge win, except for some minor problems like that MS Access can't link to a table that has BMI's defined. (But you can put the indexes on after the link is made.) > > For which rate of low cardinality do you think that is useful > to use bitmap indexes? > > > > > Regards, > -- > Luis Santos > Relacional Consultoria > Rio de Janeiro - Brazil