RE: Resetting execution plan
- From: "Laimutis Nedzinskas" <Laimutis.Nedzinskas@xxxxxxxxxxxxx>
- To: <oracle-l@xxxxxxxxxxxxx>
- Date: Thu, 30 Nov 2006 16:34:40 -0000
Oracle can get away with that.
Actually, it could be that Oracle had realized what was happening and
was changing the direction already.
Instead of repeating the old mantra "gather statistics" Oracle 10g
documented/introduced many useful hints which enable to control CBO
quite well. For example, I was impressed by the ability to hint not a
particular index but any available index on specified columns. Naming
subqueries (qb_name) is another nice feature of 10g.
________________________________
From: oracle-l-bounce@xxxxxxxxxxxxx
[mailto:oracle-l-bounce@xxxxxxxxxxxxx] On Behalf Of Wolfgang Breitling
At 08:36 AM 11/30/2006, Laimutis Nedzinskas wrote:
Ahhhr.
It sucks so much this empiric time-variant CBO thing. Out of
always bad and sometimes bad I prefer always bad.
Ask any electronics engineer what problem he prefers: the
constant one or no-no-but-yes-and-no-and-yes-and-no. I hope Oracle will
realize it one day.
Don't count on it. In my view it is only going to get worse in Oracle 11
when they activate the object cache hit statistics (it's already in 10
but disabled by default) and other dynamic CBO features.
Fyrirvari/Disclaimer
http://www.landsbanki.is/disclaimer
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