Re: Performance problems with multiple layers of functions

On Fri, Mar 24, 2006 at 01:49:17PM +0100, Svenne Krap wrote:
> explain select dataset_id, entity, sum(amount) from entrydata_current
> where  flow_direction in (select * from outflow_direction(dataset_id))
> and dataset_id in (select * from get_dataset_ids(122)) group by
> dataset_id, entity;
<snip>
> which does not return within 10 minutes - which is unacceptable.


The issue is that the planner has no way to know what's comming back
from get_dataset_ids.

I think your best bet will be to wrap that select into it's own function
and have that function prepare the query statement, going back to
hard-coded values. So you could do something like:

SQL := 'SELECT ... AND dataset_id IN (''' || get_dataset_ids(122) ||
''');' (yeah, I know that won't work as written, but you get the idea).
--
Jim C. Nasby, Sr. Engineering Consultant      jnasby@pervasive.com
Pervasive Software      http://pervasive.com    work: 512-231-6117
vcard: http://jim.nasby.net/pervasive.vcf       cell: 512-569-9461