> -----Original Message----- > From: [EMAIL PROTECTED] [mailto:pgsql-hackers- > [EMAIL PROTECTED] On Behalf Of Luke Lonergan > Sent: Friday, July 28, 2006 12:18 PM > To: Jim C. Nasby; Jie Zhang > Cc: Tom Lane; Mark Kirkwood; Josh Berkus; Gavin Sherry; pgsql- > [EMAIL PROTECTED] > Subject: Re: [HACKERS] On-disk bitmap index patch > > Jim, > > On 7/28/06 10:17 AM, "Jim C. Nasby" <[EMAIL PROTECTED]> wrote: > > > If the usefulness of bitmap indexes is still in doubt, could someone at > > Greenplum provide data from actual data warehouses from actual > > customers? > > First, is anyone in doubt?
Others have looked into the usefulness of bitmap indexes. Here is what they found: http://www.oracle.com/technology/pub/articles/sharma_indexes.html http://citeseer.ist.psu.edu/stockinger02bitmap.html Oracle, IBM, and even Microsoft[1] supports them. Probably not just to be trendy. [1] Microsoft SQL Server creates temporary bitmap indexes during some queries, though you cannot declaratively create a bitmap index. > - Luke > > ---------------------------(end of broadcast)--------------------------- > TIP 5: don't forget to increase your free space map settings ---------------------------(end of broadcast)--------------------------- TIP 9: In versions below 8.0, the planner will ignore your desire to choose an index scan if your joining column's datatypes do not match
