Re: monitor column usage or index usage?
- From: "Jonathan Lewis" <jonathan@xxxxxxxxxxxxxxxxxx>
- To: <oracle-l@xxxxxxxxxxxxx>
- Date: Fri, 7 May 2004 09:35:11 +0100
What do you mean by 'working' ?
Column usage monitoring is enabled by
default. It doesn't "do" anything, it simply
exists so that the AUTO option for generating
histograms has some data of which columns
might be appropriate for histograms.
If I recall correctly, the col_usage$ table is another
of those things handled by smon every 5 minutes.
If a hard parse of an sql statement has included
a column in its where clause since the previous
update to col_usage$, then the relevant usage
column is incremented.
Oracle 9 has a procedure
dbms_stats.flush_database_monitoring_info
to force a flush (on col_usage$ and mon_mod$),
so that you can see the effect in close to real time.
Regards
Jonathan Lewis
http://www.jlcomp.demon.co.uk
http://www.jlcomp.demon.co.uk/faq/ind_faq.html
The Co-operative Oracle Users' FAQ
http://www.jlcomp.demon.co.uk/seminar.html
Optimising Oracle Seminar - schedule updated May 1st
----- Original Message -----
From: "Michael Thomas" <mhthomas@xxxxxxxxx>
To: <oracle-l@xxxxxxxxxxxxx>
Sent: Thursday, May 06, 2004 9:22 PM
Subject: monitor column usage or index usage?
Thinking about which is better, monitor column usage
or index usage?
<big snip>
So, this appears interesting, but I haven't got it
quite working yet in my own schemas.
My question is: Does anyone know how to get this
technique working (what am I missing?)?
----------------------------------------------------------------
Please see the official ORACLE-L FAQ: http://www.orafaq.com
----------------------------------------------------------------
To unsubscribe send email to: oracle-l-request@xxxxxxxxxxxxx
put 'unsubscribe' in the subject line.
--
Archives are at //www.freelists.org/archives/oracle-l/
FAQ is at //www.freelists.org/help/fom-serve/cache/1.html
-----------------------------------------------------------------
Other related posts:
