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From Bryan Pendleton <bpendleton.de...@gmail.com>
Subject Re: I need help on getting Derby to use a primary key index on a query
Date Wed, 21 Aug 2013 23:55:08 GMT
> Any thoughts or comments on why this the optimizer chooses on over the other?

Unfortunately, no.

But there have been concerns about the optimizer's cost
analysis for years; see https://issues.apache.org/jira/browse/DERBY-1905
and some of the other issues linked from it (DERBY-1259, DERBY-1260).

So, while I know it's frustrating for you to be wrestling with
an optimizer that won't behave, it's also good news, for Derby,
that you've made such good progress in trying to understand
this peculiar behavior.

Perhaps when we get to the bottom of the strange behavior
you're seeing, we'll have a better understanding of some of
the other strange optimizer behaviors we've seen in the past.



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