Bitmap indexes - when to use?

I'd like to know if using bitmap indexes on a column such as STATE would be a good idea. My impression is that bitmaps would be useful only in situations with low cardinality in the column (yes/no, on/off etc). With a STATE column in a table of, say, 6 million rows, you could have, at most, 50 distinct values. Would it be better in this case just to go with a regular B-tree index? BTW, in this case the STATE column in the main table is an FK to the STATE_CD lookup table and this is for a DSS type db using partitions.

(Oracle 8.0.5 on Solaris)

Any input appreciated.

Thanks

mkb Received on Thu May 20 1999 - 10:55:08 CDT