Re: Join question

about 5% of b are null..   any idea on how to word a query like what I'm
looking for? I have no idea in SQL how to use the results of one select
in another (I usually just do all of it in perl).

Travis

-----Original Message-----
From: Jeffrey Melloy [mailto:jmelloy@visualdistortion.org]
Sent: Friday, August 29, 2003 12:44 AM
To: Williams, Travis L, NEO
Cc: Thomas A. Lowery; pgsql-general@postgresql.org
Subject: Re: [GENERAL] Join question



On Friday, August 29, 2003, at 12:36  AM, Williams, Travis L, NEO wrote:

> Performace wise would I be better off just doing 2 query's.. i.e.
> select
> a,b from table1.. then in perl I can check if b is not null and if is
> isn't then I do a second query?
>
> Travis
>
I would say it depends on the table distribution (% of b that are null,
etc).  At that point, you're just going to have to experiment, I think,
and see what works best for you.  My gut says that even including a
subselect, it will be faster than checking in perl and issuing another
query.  But I have no idea, and the proper solution might change
drastically based on your data.

Jeff