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From:Joseph Bueno Date:September 18 2003 3:56pm
Subject:Re: Slow query join problem
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Allen wrote:
> I have two tables.  One table is 13 million rows the other is about 
> 250,000.  I am trying to join the two to find users.  The tables are not 
> indexed and I know that will effect the speed, but the join never 
> completes.  I let it run for about 10 hours and the process was stuck in 
> the "sending" state, which I don't really understand.  What is taking so 
> long?  The join size should be no greater than 250,000 which is the size 
> of the second table.  Yes??? 
> I am using the default join_buffer size, which seems to low.  Might this 
> be the problem?
> 
> 
Well, running a join on tables without indexes is like running a simple
select on a table that is the cartesian product of both tables.
In your case, you are trying to run a select on a table with:
13million x 250,000 = 3,250,000,000,000 rows !

I am afraid that you won't get any result soon, even with a big join
buffer :(

Regards,
Joseph Bueno

Thread
Slow query join problemAllen18 Sep
  • Re: Slow query join problemDan Nelson18 Sep
    • Re: Slow query join problemAllen18 Sep
  • Re: Slow query join problemJoseph Bueno18 Sep