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Re: After partition also select is scanning all the partitions - need help
Posted by: Rick James
Date: September 21, 2010 04:18PM

And I claim that the number in EXPLAIN does not prove anything. It does point out that it is not hitting all the partitions. I think that is stronger evidence that it is not scanning the entire table.

Here's another approach to actually count the rows hit...

SHOW SESSION STATUS LIKE 'Handler%';
SELECT ... WHERE ...
SHOW SESSION STATUS LIKE 'Handler%';

Now take the differences between the Handler values.

Repeat with a different WHERE clause. See if certain of the Handler deltas are more in line with what you expect.

(If the table were 8M rows instead of 8K, I would suggest using a stopwatch.)

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Re: After partition also select is scanning all the partitions - need help
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September 21, 2010 04:18PM


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