Re: Indexes not used

From: Stephen Ashmore <sashmore_at_neonramp.com>
Date: Tue, 5 Mar 2002 19:47:46 -0000
Message-ID: <u8at7s2o11mr1f@corp.supernews.com>

Also check to ensure
db_file_multiblock_read_count
are the same.
This parameter can influence the optimizer to do full table scans.

Stephen C. Ashmore
Brainbench MVP for Oracle Administration http://www.brainbench.com

"Ralph Graulich" <ralph_at_grauli.ch> wrote in message news:ralph-CF6943.18374305032002_at_doorway.ih.reiff.de...
> 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 ...
Received on Tue Mar 05 2002 - 13:47:46 CST