RE: Performance Problems

Tried the RULE hint and did not help. This is a large production DB, so any gotchas/cons I need to worry about when collecting stats on SYS? Don't want to make things worse...

Also, have done the 10046 trace and seeing bunch of "db file sequential read" and "buffer busy wait" waits.

Thanks!

-----Original Message-----

From: Bobak, Mark [mailto:Mark.Bobak_at_il.proquest.com] Sent: Thursday, March 23, 2006 10:39 AM
To: Ebadi, Abdul; oracle-l_at_freelists.org Subject: RE: Performance Problems

Try the RULE hint, does that speed things up? If that doesn't do it, try collecting stats for SYS.

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Mark J. Bobak
Senior Oracle Architect
ProQuest Information & Learning

For a successful technology, reality must take precedence over public relations, for Nature cannot be fooled. --Richard P. Feynman, 1918-1988

-----Original Message-----

From: Ebadi, Abdul [mailto:Abdul.Ebadi_at_Level3.com] Sent: Thursday, March 23, 2006 12:29 PM
To: Bobak, Mark; oracle-l_at_freelists.org
Subject: RE: Performance Problems

Optimizer mode is CHOOSE. We have not gathered stats on the data dictionary. Last_analyzed is null for all SYS/SYSTEM-owned tables.

Thanks!

-----Original Message-----

From: Bobak, Mark [mailto:Mark.Bobak_at_il.proquest.com] Sent: Thursday, March 23, 2006 10:24 AM
To: Ebadi, Abdul; oracle-l_at_freelists.org Subject: RE: Performance Problems

What is optimizer_mode set to?

Have you tried the query with a /*+ RULE */ hint?

Have you considered gathering statistics on the data dictionary?

-Mark

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Mark J. Bobak
Senior Oracle Architect
ProQuest Information & Learning

For a successful technology, reality must take precedence over public relations, for Nature cannot be fooled. --Richard P. Feynman, 1918-1988

-----Original Message-----

From: oracle-l-bounce_at_freelists.org
[mailto:oracle-l-bounce_at_freelists.org] On Behalf Of Ebadi, Abdul Sent: Thursday, March 23, 2006 12:20 PM
To: oracle-l_at_freelists.org
Subject: Performance Problems

We have a large datawarehouse database on Oracle and are encountering strange performance problems. A query such as "select count(*) from dba_data_files;" will run in a few seconds or as long as 15 minutes depending on when this is run. We've narrowed it down to where it is not even directly related to load on the DB. A few days ago, I ran this query right after we started the DB (no activity in the DB at all) and it took 6 minutes! The waits we were seeing were "db file sequential read" and "buffer busy wait" for this query. Keep in mind our DB is ~27TB with ~30,000 datafiles!

Oracle 9.2.0.4 on Solaris 10.

Any help will be appreciated.

Thanks!
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http://www.freelists.org/webpage/oracle-l

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http://www.freelists.org/webpage/oracle-l Received on Thu Mar 23 2006 - 11:50:17 CST