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Re: convert myisam to innodb - table status
Posted by: Rick James
Date: January 13, 2013 12:00AM

There are many reasons why the two engines are different.

Yes, defrag could have been a side effect causing the shrinkage.

The effect of DELETEs is different between the engines -- each recovers some of the space, but in different ways.

InnoDB is _often_ 2x-3x bigger than MyISAM, mostly because of the how the data is laid out.

Then there is space/overhead for transactions.

Indexes are rather different. A wide PRIMARY KEY takes a lot of space in MyISAM, but almost none in InnoDB since it is 'clustered' with the data.

Secondary keys may be fatter in InnoDB because they contain the PK instead of a 6-byte pointer to the data.

CHAR, TEXT, and BLOB are handled rather differently, leading to more or less space consumed.


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Written By
December 03, 2012 06:09AM
Re: convert myisam to innodb - table status
January 13, 2013 12:00AM

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