Re: [SQL] query with subquery abnormally slow?

have you tried to:  
explain <your select statement> 
to see the cost of the parts?

I would try this.  Then I would try a :
create index <indexname> on items (package)
and repeat the explain to see if it changes the cost.

Bill

On Mon, Nov 01, 1999 at 09:10:30PM +0100, Oskar Liljeblad wrote:
>On Mon, Nov 01, 1999 at 07:47:07PM +0100, Oskar Liljeblad wrote:
>> I'm doing a SELECT query with a subquery on a table with 12K rows
>> but it is very slow (10 seconds+). The query looks like this:
>> 
>>   select *
>>     from items
>>     where package in
>>       (select package
>>          from items
>>          where ...blah...
>>          group by package)
>
>I could do it much faster with this query:
>
>  select distinct i2.package, i1.*
>  from items i1, items i2
>  where i1.package = i2.package
>  and ...blah...
>
>but it is still at least three times slower than
>doing the subquery first, and for each row in the
>result another query. Any ideas?
>
>Oskar Liljeblad (osk@hem.passagen.se)
>
>************
>

Bill Brandt                                   
brandtwr@draaw.net                              http://www.draaw.net/