RE: Different Plans for Literal Vs Bind Variables
- From: "Allen, Brandon" <Brandon.Allen@xxxxxxxxxxx>
- To: "ian@xxxxxxxxxxxxxxxxx" <ian@xxxxxxxxxxxxxxxxx>, Oracle-L Freelists <oracle-l@xxxxxxxxxxxxx>
- Date: Fri, 9 Jan 2009 16:14:41 -0700
The phrase "would not have been" indicates an assumption to me and you know
what happens when we assume :-) I would leave nothing to chance and check
v$sql for the specific hash_value that appears in your raw 10046 trace file to
be 100% positive that the query is not loaded in your library cache before you
run it with the desired bind variable value. Then, if you verify that it gets
hard parsed with the desired bind value and still doesn't get the same plan as
the literal, I think your next step is to run two 10053 traces and diff them.
In case you're not familiar with the 10053 trace, here's a good place to start:
http://www.centrexcc.com/A%20Look%20under%20the%20Hood%20of%20CBO%20-%20the%2010053%20Event.pdf
Regards,
Brandon
-----Original Message-----
From: oracle-l-bounce@xxxxxxxxxxxxx [mailto:oracle-l-bounce@xxxxxxxxxxxxx] On
Behalf Of Ian MacGregor
The statements were new so they
would not have been in the library cache, and the values reported for the
10046 level 12 trace matched those in the query with literals
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