Re: Indexes not used

On Tue, 05 Mar 2002 18:37:43 +0100, Ralph Graulich <ralph_at_grauli.ch> wrote:

>Hi,
>
>
>> In a different oracle instance (schema created by same third party
>> software), the indexes are not being used. Full table scans are
>> happening. Hash joins are used.
>
>There are many different problems, which cause indexes being used in one
>or another way. The most common ones to check are:
>
>a) What kind of optimizer is used (cost based / rule based)?
>b) Are the tables fully analyzed (ANALYZE TABLE <tablename> COMPUTE
>STATISTICS)?
>c) Is there any configuration directive in the init.ora file which
>prevents Oracle from using HASH_JOINS?
>d) In case hints are used: Are they written correctly?
>
>
>Regards
>... Ralph ...
 

And along with point A, what are the data volumes on the different instances. If one is a test instance with only 10% of the data as the other, it will tend to favor full table scans.

--
Ed Stevens
(Opinions expressed do not necessarily represent those of my employer.)