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Home -> Community -> Mailing Lists -> Oracle-L -> Re: Curious question about flushing the Pool
It sounds a cute idea at first sight (pardon the mixed metaphor) - but then what do you do about the situation where you deliberately have a handful of versions of the 'same' SQL which are identified by the presence of a literal string; or the SQL that you build with one literal and many binds because that one literal is required to make sure that Oracle uses a histogram on one column ?
Then there's the problem of literals which are textually constant but variable valued such as:
sys_context('hr_hierarchy','manager');
Marginal proliferation of 'semi-literate' <joke> SQL can be a good thing. Maybe yet another undocumented hint /*+ bypass_cache_flush */ would be sufficient.
One (trivial ?) thing I'd like to see is SQL normalised before it goes into the shared pool. Oracle 9i does it with stored_outlines - why not with all SQL ?
Jonathan Lewis
http://www.jlcomp.demon.co.uk
Author of:
Practical Oracle 8i: Building Efficient Databases
Next Seminar - Australia - July/August
http://www.jlcomp.demon.co.uk/seminar.html
Host to The Co-Operative Oracle Users' FAQ http://www.jlcomp.demon.co.uk/faq/ind_faq.html
-----Original Message-----
To: Multiple recipients of list ORACLE-L <ORACLE-L_at_fatcity.com>
Date: 25 April 2002 05:00
I think an excellent Oracle kernel enhancement would be to bias in the
LRU scheme against SQL that uses literals, just like the buffer cache
algorithm biases against blocks that are read via full-table scan.
Think
about it... What's the likelihood that a SQL statement that's filthy
with literal values will ever be reused again in the future? Then why
store it as if it will ever be shared (i.e., reused) in the future?
Cary Millsap
Hotsos Enterprises, Ltd.
cary.millsap_at_hotsos.com
http://www.hotsos.com
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Please see the official ORACLE-L FAQ: http://www.orafaq.com
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Author: Jonathan Lewis
INET: jonathan_at_jlcomp.demon.co.uk
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