Coming a close second to the “rebuild indexes regularly” fairy tale is the “a column with a small number of distinct values is a good candidate for a bitmap index” legend.
I’ve had to explain the error in the legend three times in the last month, so I thought I’d just point to a series of articles I wrote some time ago that might save people from wasting too much effort the next time they start to play with bitmap indexes.
- Introduction to bitmap indexes (ca. 1999)
- Bitmap indexes (ca. 2003)
- Star Transformations (ca. 2003)
- Bitmap Join indexes (ca. 2003)
All four articles were written several years ago; so when you review them, remember the advice I gave in an earlier post.