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From Army <qoz...@gmail.com>
Subject Re: [jira] Commented: (DERBY-2130) Optimizer performance slowdown from 10.1 to 10.2
Date Wed, 13 Dec 2006 17:57:46 GMT
Bryan Pendleton wrote:

> Independently, I tried fiddling with the cost estimates myself, because as
> I stepped through HeapCostController and BTreeCostController, my reaction
> was that the costs were possibly 2 orders of magnitude too high. In my
> experiments, I didn't see much benefit to the optimizer, but I wonder if
> that's because I *also* need to have some of these other fixes (such as the
> permute state fix from jumpReset.patch and the JUMPING-give-up change that
> you've been studying) in order for the cost estimate changes to take 
> effect?

I was actually going a very different direction with this.  I don't know 
anything about the CostControllers so I tend to avoid them, perhaps to my 
detriment ;)

I've attached a partial patch with my (potentially completely wrong) approach to 
DERBY-1905.  Feel free to look at that and comment/fix it up as needed.  I don't 
have time at the moment to pursue those changes and will not be able to until at 
least next year...


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