RE: db file scattered/sequential read wait

That background job does not have the where clause " where p2 between block_id and (block_id+blocks-1)" it just reads dba_extents (same as my nightly job does). It takes a while, but it does it only once. I was referring to the fact that the OP was monitoring db_file_... wait events and was warning against frequent executions of the sql in order to determine the object name. That sql does practically the same work as the batch jobs and then throws away most of the result set. Try doing that frequently with tables/indexes in LMTs and see what happens. I still don't find it a good idea to run that job every hour during prime time, but hey, whatever turns you on.

<soapbox>
Interesting idea. Buying spare expensive cpu cycles so that you can run that sort of stuff, but then balk at the cost of disk and go with raid5 because it is cheaper.
</soapbox>

I am not insinuating that that is the case at your shop, but I am confident that there is enough of this around.

Quoting Roger Xu <roger_xu_at_dp7uptx.com>:

> We are running SAP and there is a hourly background job which
> runs SQL against dba_segmen and dba_extents. I believe the
> program name is SAPLSDO0. Anyway, my question is: why it never
> bring down our databases?
>

-- 
regards

Wolfgang Breitling
Oracle 7,8,8i,9i OCP DBA
Centrex Consulting Corporation
www.centrexcc.com

----------------------------------------------------------------
Please see the official ORACLE-L FAQ: http://www.orafaq.com
----------------------------------------------------------------
To unsubscribe send email to:  oracle-l-request_at_freelists.org
put 'unsubscribe' in the subject line.
--
Archives are at http://www.freelists.org/archives/oracle-l/
FAQ is at http://www.freelists.org/help/fom-serve/cache/1.html
-----------------------------------------------------------------