Re: Bitmap indexes - when to use?

>In this case, I say go with nromal B-Tree index.
>Bitmap is suitable for:
>- low-cardinality columns e.g Yes/No, Married/Single, Male/Female.
>- Efficient for queries using OR predicates
>- Usefull for DSS (Decesion support system)
>-Infrequent updates

I would have to disagree with this particular solution (with all due respect). Bitmap indexes are suitable for low-cardinality columns, true. But this does not mean a cardinality of 2 or three. With thousands of records, a cardinality of 50 is pretty low. Also, it was stated that the STATE column is a foreign key. B-tree indexes do not foster cooperativity among other indexes like Bitmap indexes do. This cooperativity is highly desired in the join operations on low-cardinality attributes. If you'd like more information on this, I'd be happy to email a copy of my Masters thesis which is titled "Orthogonal Bitmaps for Hybrid Hash Join". This just happens to be a subject near and dear to my heart.

 In the case described by the original post I'd use bitmap indexes. I guess this just goes to show how two people can have two differing opinions depending on their point of view.

Hope this helps,
Brian Peasland
peasland_at_msn.com Received on Thu May 20 1999 - 22:31:02 CDT