Re: When to use bitmap indexes

I've had quite a bit of experience with these. Yes, it's a matter of trial and
error. Do some timings and check the optimiser's query plan via tkprof or Enterprise manager. I have seen some major, major improvements when I've indexed on columns having 1000 different keys in a million row table,
so it does work!!!

Regards,

Phil Edmonds
Enterprise Database Manager
Salisbury Health Care NHS Trust

Philip Zubaly wrote in message <36631ac8$0$26846_at_mojo>...
>I understand that bitmap indexes are efficient for columns with a fairly
small
>and static set of values, but am interested in gathering any information
that I
>can on experience with them to help in decision making for a number of
cases.
>
>Several cases seem perfect candidates for bitmap indexes -- y/n columns
which
>are often used in queries. But what about a column with 50 values and
100,000
>records? What if values would be added every once in a while?
>
>Is it all pretty much trial and error, or can the decision be quantified in
any
>way?
>
>thanks --
>
>
>
>
Received on Fri Dec 04 1998 - 14:23:36 CST