From: bowen
Date: October 11 2006 1:33am
Subject: Re: Why does mysql drop index very very slow in a large table?
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>
> 1) create table T1 like T;
> This creates an empty table T1 with indexes ndx1,ndx2,ndx3 and ndx4.
> 2) alter table T1 drop index ndx3;
> This drops index ndx3 on the empty T1, which should be instantaneous.
> 3) insert into T1 select * from T;
> This will populate table T and load all three(3) indexes for T1 in one pass.
>
Insert millions of rows into table  should be very slow, and obviously
be not efficient. Can I use `cp -f T.MYD T1.MYD` instead ?

> 4) drop table table T;
> 5) alter table T1 rename to T;
>