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Re: Derived tables optimized differently than when directly queried?
Posted by: Björn Steinbrink
Date: October 26, 2006 05:33PM

I've filed a bug for that some time ago. http://bugs.mysql.com/bug.php?id=18493

That the explain output shows no possible keys means, that it cannot do a lookup using the key (without scanning the whole index). And in that case, it does an index scan, because all required values are found in the index (so it can avoid the full table scan), so it's using a key, but not in the usual way.

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Derived tables optimized differently than when directly queried?
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Tom Callahan
October 25, 2006 02:38PM
Re: Derived tables optimized differently than when directly queried?
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Björn Steinbrink
October 26, 2006 05:33PM


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