_optimizer_cost_based_transformation=OFF risks

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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