_optimizer_cost_based_transformation=OFF risks
- From: <saqibz@xxxxxxxxxxx>
- To: <oracle-l@xxxxxxxxxxxxx>
- Date: Wed, 24 Oct 2007 12:01:43 -0400
Hello All,
We are using Oracle 10.2.0.3 on SPARC 64 bit with patches applied up to
CPUJul2007. Even since our upgrade from 10.2.0.2, we have started to hit
bug#4686006. The good thing is that there is a patch available, which we will
apply as soon as we get the red tape issues worked out. An alternate workaround
mentioned in the metalink doc#392551.1 is to unset the
_optimizer_cost_based_transformation parameter. I can understand that by
turning it off I would be relying on heuristics for SQL transformations i.e.
view merging, predicate push or un-nesting etc. But, by setting it at the
system level, wouldn't that leave out a lot of good stuff that would have come
to use because of the cost based SQL transformations. I guess my question is,
what should i should be looking out for and if anyone can share their
experiences with similar issues(good, bad or ugly) after changing the
_optimizer_cost_based_transformation=OFF
regards,
saqib
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