From: Dan Nelson
Date: November 21 2002 11:22pm
Subject: Re: irrelevant multi-column index yields incredible speedup!
List-Archive: http://lists.mysql.com/mysql/125595
Message-Id: <20021121232205.GF86807@dan.emsphone.com>
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In the last episode (Nov 21), johnt@stripped said:
> Adding an irrelevant second column to an index instead of just a
> single column index gives an incredible speedup and I don't know why!

If you then remove the index, is it still fast?  Maybe you are just
seeing the results of mysql rebuilding the state key.  When you modify
an index, I believe mysql ends up rebuilding all indexes on that table.
"optimize table mytable" would probably have given you the same speed
boost.

-- 
	Dan Nelson
	dnelson@stripped