NYCPHP Meetup

[Andrew Yochum]

On Thu, Oct 21, 2004 at 05:41:27PM -0400, Stephen Musgrave wrote:
> So, I thought this query would be easy, but I've spent the better part 
> of an afternoon on it.  To put it mildly:  it's very slow.  Any tips on 
> how i might speed it up would be greatly appreciated.
> 
> SELECT
> 	a.column1
> 	COUNT(DISTINCT c.column1) as column1_count
> FROM
> 	table1 a,
> 	table2 b,
> 	table3 d,
> 	table4 h
> WHERE
> 	a.column2 = 1 AND a.column3 = 1
> 	AND (c.column3 = a.column3 AND c.column2 = a.column2)
> 	AND (d.column3 = a.column3 AND d.column2 = a.column2)
> 	AND (h.column3 = a.column3 AND h.column2 = a.column2)
> GROUP BY
> 	a. column3
> HAVING
> 	(column1_count >= 2)

Do you have indexes on column2 and column3 on each of the tables?

The output of explain would probably be helpful.  Just put the word
"explain" before the select.