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Home -> Community -> Mailing Lists -> Oracle-L -> RE: Why isn't Oracle Using My Index
Greetings,
Thanks to Riyajh Shamsudeen for pointing out to me that NLS_SORT is in part the culprit. In our database NLS_SORT = GENERIC_BASELETTER. According to the Oracle documentation this forces a full table scan. I set nls_sort=binary and the query used the indexes. I still don't fully understand what is going on and need to do some further reading. I also need to turn on cpu_costing and see if that will resolve the problem if nls_sort is left at it's current setting. Thanks to all who responded, I truly appreciate the help.
SQL> select * from table(dbms_xplan.display);
PLAN_TABLE_OUTPUT
| 0 | SELECT STATEMENT | | 416 | 226K| 1430 | |* 1 | TABLE ACCESS FULL | T185 | 416 | 226K| 1430 |
--------------------------------------------------------------------
Predicate Information (identified by operation id):
PLAN_TABLE_OUTPUT
1 - filter(NLSSORT("T185"."C1")=NLSSORT('HD0000000041608'))
Note: cpu costing is off
Bill Wagman
Univ. of California at Davis
IET Campus Data Center
wjwagman_at_ucdavis.edu
(530) 754-6208
From: Jared Still [mailto:jkstill_at_gmail.com]
Sent: Thursday, December 21, 2006 11:20 AM
To: Thomas.Mercadante_at_labor.state.ny.us
Cc: William Wagman; oracle-l_at_freelists.org
Subject: Re: Why isn't Oracle Using My Index
On 12/21/06, Mercadante, Thomas F (LABOR) <Thomas.Mercadante_at_labor.state.ny.us> wrote:
Bill,
When you run the query, how fast is the response?
Just to add a bit to Tom's response:
Why not do a 10046 trace on the query?
Run it both with and without the index hint and compare the results.
An excellent method for comparing the 2 would be to use runstats - http://asktom.oracle.com/tkyte/runstats.html
HTH
-- Jared Still Certifiable Oracle DBA and Part Time Perl Evangelist -- http://www.freelists.org/webpage/oracle-lReceived on Thu Dec 21 2006 - 17:02:53 CST
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