RE: oracle recompiling sql the same sql repeatedly?
- From: "Jesse, Rich" <Rich.Jesse@xxxxxx>
- To: <ryan_gaffuri@xxxxxxxxxxx>, <oracle-l@xxxxxxxxxxxxx>
- Date: Thu, 22 Jun 2006 10:41:50 -0500
Hey Ryan,
I would challenge Support to defend using CS=S for you. This is really
not a situation where one should use it. For us, it was either recode
all of our programs to use bind variables (when we started with Oracle,
we didn't know how important they were), use CS=S, or have nightmares
about the shared pool. So I chose the lesser of all evils, CS=S. And
it hasn't been without it's problems. There have been bugs where some
queries would return incorrect data. And a recent ORA-6500 bout may be
affected by CS=S (although less likely).
Don't take a decision to use CS=S lightly!
HTH! GL!
Rich
________________________________
From: oracle-l-bounce@xxxxxxxxxxxxx
[mailto:oracle-l-bounce@xxxxxxxxxxxxx] On Behalf Of
ryan_gaffuri@xxxxxxxxxxx
Sent: Thursday, June 22, 2006 9:37 AM
To: oracle-l@xxxxxxxxxxxxx
Subject: oracle recompiling sql the same sql repeatedly?
I have a test box. I am testing some things out. I noticed excessive row
cache waits, so I ran this generic query:
select substr(sql_text,1,100),count(*)
from v$sql
group by substr(sql_text,1,100)
having count(*) > 500
order by 2
I found that some of my test sql was recompiling repeatedly.
1. I am using bind variables and I am not using dynamic sql.
2. I was not able to do a select count(distinct sql_fulltext) from v$sql
because its a clob, so I copied the sql to a new table with a
varchar2(4000) column.
3. I did a select count(distinct sql_fulltext) from mydifftable and I
got 1 row back.
4. Copied to rows from v$sql with this sql to files locally and ran an
open source diff utility on them and got the exact same sql.
Why would oracle recompile the same sql? It is run out of the same
schema? Oracle support recommended that I use cursor_sharing=similiar;
before I do that I want to understand why this is happening.
Anyone see this before? I am on 10g release 2. Maybe I missed something
in the docs?
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