Re: Experience in bitmap index in Oracle 7.3

Bitmap indexes are a good performance booster when you are dealing with highly repetative data. On Sun Solaris you must have oracle release 7.3.2.3 and set
compatabiltiy = 7.3.2.

You need to analyze the table either by estimation or computation, and it is highly recommended that you use the parallel query options. In general the indexes should be of a single field, since multiple bitmap indexes can be used in a parallel query. During our conversion to bitmap indexes we had a reduction in index size on 1 field from 438 megs to 700k. The table contains 12 million rows of data and field was on the state abbreviation char(2). The query time to count records where state = 'NY' went from 1.38 seconds to .02 seconds.

In total we have reduced our total index storage requirements by 70% and increased the performance of the system by 62%. If have specific questions you can e-mail me directly.

-- 
Ray Stafford
rstaffor_at_lcp.com

Chun Cheng <chun.cheng_at_sas.se> wrote in article <32FA6519.3CD6_at_sas.se>...


> Hi there

> 

> Can somebody tell me how I can use bitmap indexing in Oracle 7.3. and

> where I can find it in the documentation ?

> 

> I have been told that it can boost my querys. But I need some

> information or experience from out there.

> 

> I hope indeed it have some interest for other DBA which have same

> problems.

>