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From Jeffrey Lichtman <swa...@rcn.com>
Subject Re: Derby-573 Optmier overrides - joinOrder and joinStrategy
Date Wed, 08 Feb 2006 21:19:00 GMT
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<blockquote type=cite class=cite cite="">One of optimizer overrides, that
a user can specify, is joinStrategy. The functional spec for joinStrategy
says following &quot;The joinStrategy property can be used only within a
TableExpression, <u>but it must be used in conjunction with the joinOrder
property. Do not let the optimizer choose the join order.
</u>&quot;</blockquote><br>
I think this should be stated as a piece of advice, not as an absolute
rule. Generally, specifying a join strategy doesn't make much sense
unless you already know the join order. That is, the same join strategy
wouldn't necessarily be optimal for different join orders. But specifying
the join strategy without specifying the join order won't prevent the
query from running (except perhaps in some corner cases), nor will it
cause the query to return the wrong results.<br>
<x-sigsep><p></x-sigsep>
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-&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Jeff Lichtman<br>
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