From: Eric Bergen
Date: December 4 2004 4:56am
Subject: Re: Help me optimize this query
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If you change the update to a select you can use explain to see it's
execution path just like you would with a normal select. The rows
returned are the rows that would be matched by the update query.
Example:

explain select * from t1, t2 where t1.YYY=t2.ZZZZ and t2.AAAA like '%X%';

Optimize the query then turn it back into an update. 

-Eric


On Wed, 1 Dec 2004 11:38:29 +0530, Manish <prolist@stripped> wrote:
> I am trying to execute this query and it is failing with Table is full error
> (I know I can make temp tables big).
> update t1, t2
> set t1.XXX=1
> where t1.YYY=t2.ZZZZ and t2.AAAA like '%X%';
> 
> My t1 has 10,00,000+ records and t2 has about 70,000 recorsds. I would like
> to know how can I optimize this query?
> What are the parmeters for this optimization? Can someone give me links
> where I can read up about such optimizations for update query.
> 
> TIA,
> - Manish
> 
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-- 
Eric Bergen
eric.bergen@stripped
bleated.com