On Tue, 20 Apr 1999, Getman, Aric wrote:
> Ari,
> Just received a new assignment to perform research on Optimizer (cost vs.
> rule).  Are there any excellent books or publications on this topic that you
> recommend?
> Also, what is bitmap index?
> Thanks for your help,
> Ace


There was a speech on this subject alone last week at the IOUG-A '99 in
Denver. Check out www.ioug.org to get the paper and/or powerpoint. They
have a link to get it on cassette tape as well.

My opinion is that the optimizer in Oracle8 is much more stable than in
Oracle7. If you have a combination of large tables and small tables, I
would recommend it in Oracle7 although it would be less predictable.

A bitmap index (Oracle8 only) is used for "low-cardinality" columns. For
example, a column with only "TRUE" or "FALSE" with a million records would
be terrible for a regular index but for bitmap indexes it is quite good.
Bitmap indexes are stored in binary (compressed) and so take up about only
10 of regular indexes.

Best regards,

-Ari Kaplan
Independent Oracle DBA Consultant

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