Re: select count(*)
- From: "Jonathan Lewis" <jonathan@xxxxxxxxxxxxxxxxxx>
- To: <oracle-l@xxxxxxxxxxxxx>
- Date: Fri, 6 Oct 2006 17:12:51 +0100
Cut off the right-hand columns - we just need the
operations/object bit - and then paste it into the email.
Don't forget the predicates section.
Basic view - anything which is a descendent of
the FILTER (null is not null) should not happen.
It is possible (though very unlikely) that the extra
time is simply some side-effect of extra parse time
in 10gR2 compared to 10gR1. But a parse time of
31 minutes is rather unlikely.
Check your session statistics:
connect
run query
select name, value from v$mystat ms, v$statname sn
where ms.statistic# = sn.statistic#
and value != 0
Where are the biggest changes in the stats
Regards
Jonathan Lewis
http://www.oracle.com/technology/community/oracle_ace/ace1.html#lewis
The Co-operative Oracle Users' FAQ
http://www.jlcomp.demon.co.uk/faq/ind_faq.html
Cost Based Oracle: Fundamentals
http://www.jlcomp.demon.co.uk/cbo_book/ind_book.html
----- Original Message -----
From: "Sarma Aryasomayajula" <avnsarma@xxxxxxxxxxx>
To: <jonathan@xxxxxxxxxxxxxxxxxx>; <oracle-l@xxxxxxxxxxxxx>
Sent: Friday, October 06, 2006 5:05 PM
Subject: Re: select count(*)
Hi Jonathan,
Thank you very much for answer and you are right, in predicate section it
says null is not null.
I did the explain plan but I am not sure wether I can attach here or not?
one other thing I observed is, in 10gR1 I see sort group by in the plan
whereas in 10gR2 it is hash group by.
When I checked metalink for hash group by I got a link which says it is a bug.
Subject: Wrong Results Possible on 10.2 When New "HASH GROUP BY" Feature
is Used
Doc ID: Note:387958.1
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