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Re: size of TMD relative to MYD and MYI
Posted by: Rick James
Date: February 14, 2012 11:43AM

OPTIMIZE rebuilds the table (TMD is the temp copy of MYD).
* If there was lots of empty space, then the TMD will not get to be as big as the MYD.
* If there was little need for the OPTIMIZE, it will get to be as big.
* OPTIMIZE is rebuilding the data, defragmenting any rows that were split; this can involve extra disk seeks.
* OPTIMIZE will rebuild all the indexes -- this _could_ be very time consuming, especially if the indexes are 'random'.
* 0.7/11 is about 6%, but do _not_ expect it to be 6% finished. Random indexes (especially) get slower and slower.

What is the value of key_buffer_size? Normally it should be 20% of available RAM. For this operation, 50% might be better.

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