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From Bryan Pendleton <bpendle...@amberpoint.com>
Subject Re: [jira] Commented: (DERBY-2130) Optimizer performance slowdown from 10.1 to 10.2
Date Thu, 30 Nov 2006 21:50:26 GMT
 >  * I did not see the non-deterministic behavior that Bryan did
 > with 10.2 trunk--instead, I consistently see 7+ minutes.  However,
 > I only ran the query 3 times, which is probably not enough to have
 > seen what Bryan saw.  Also note that I only ran the DDL one time
 > and then I re-ran the query the second two times.  So given Mike's
 > previous comment, this may be the reason I didn't see the variance that Bryan did.

Thanks for all the help and good suggestions so far -- they have given
me a lot of ideas to pursue.

I think that Mike's theory about the source of the non-determinism
being due to whether I recreate the tables each time, or re-use the
existing tables, is a good one, and I'll see if I can confirm it
with more tests of my own.

Meanwhile, I'll also investigate the other pointers you passed along.

Regarding the comment that the DERBY-2130 test case is a hairy one,
and it would be easier to start with a simpler one, I agree. On the
other hand, the appeal of the DERBY-2130 test case is that:
a) it is complicated enough to vividly show that there is a problem
b) it is still pruned down enough so that it runs; some of my other
test cases ran for hours and "never" terminated :)

Again, thanks for all the help and ideas; they are much appreciated.

bryan



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