Posted by Aurimas Mikalauskas

Suppose you want to remove auto_increment from 100G table. No matter if it’s InnoDB or MyISAM, you’d usually ALTER TABLE `huge_table` CHANGE `id` `id` int(6) NOT NULL and then wait hours for table rebuild to complete. If you’re unlucky i.e. you have a lot of indexes and not too much RAM - you could end up waiting days. If you want to make this happen quick - there’s another way. Not documented, but works well with both - InnoDB and MyISAM.
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