And about being efficient:
On Thu, Aug 25, 2005 at 08:01:26AM -0700, Bill Moseley wrote:
> DROP VIEW cl;
> CREATE VIEW cl (id, class_time, instructor)
> AS
> SELECT DISTINCT ON(class.id)
> class.id, class.class_time, person.first_name
> FROM class, instructors, person
> WHERE instructors.person = person.id
> AND class.id = instructors.class;
And in a case like above, I'm displaying the list a page at a time.
So I first do a count to find total rows and then a select:
select count(*) from cl where class_time >= now();
select * from cl where class_time >= now() LIMIT 20 OFFSET 40;
I looked at the EXPLAIN ANALYZE for both and both do the join, it
seems. I guess it has to be that way.
So would it be smart to do the initial count on "class" instead
of the view first?
select count(*) from class where class_time >= now();
select * from cl where class_time >= now() LIMIT 20 OFFSET 40;
That is, Postgresql won't figure out that it only need to look at one
table, right?
--
Bill Moseley
moseley@hank.org
