Re: CBO histograms and bind variable

From: Geomancer <pharfromhome_at_hotmail.com>
Date: 11 Oct 2003 17:06:14 -0700
Message-ID: <cf90fb89.0310111606.3619d03c@posting.google.com>

> Is there differences between versions 8 and 9?

Great changes, I hear.

Yes, CBO peeking with histograms started in 9i, but there's lots more goodies.

Best is the automatic detection (skewonly) and creation of histograms only where they are needed:

--*************************************************************
-- SKEWONLY option—Detailed analysis
--
-- Use this method for a first-time analysis for skewed indexes

-- This runs a long time because all indexes are examined

--*************************************************************
 

begin
  dbms_stats.gather_schema_stats(

     ownname          => 'SCOTT',
     estimate_percent => dbms_stats.auto_sample_size,
     method_opt       => 'for all columns size skewonly',
      degree           => 7

   );
end;

Here is the OTN article:

http://otn.oracle.com/oramag/webcolumns/2003/techarticles/burleson_cbo_pt1.html Received on Sat Oct 11 2003 - 19:06:14 CDT