From: Andreas Joseph Krogh <andreak@officenet.no>
Organization: OfficeNet AS
To: pgsql-sql <pgsql-sql@postgresql.org>
Subject: Returning the total number of rows as a separate column when using
	limit
Date: Wed, 31 Oct 2007 16:55:51 +0100
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Hi.

AFAICS the information about the *total* number of rows is in the "result"=
=20
somehow. When I execute a "limit 1" query with EXPLAIN ANALYZE, I se the=20
total number of columns in "rows=3D200819", so the information is there.

andreak=3D# EXPLAIN ANALYZE select p.id from onp_crm_person p order by p.cr=
eated=20
DESC limit 1;
                                                                           =
=20
QUERY PLAN
=2D------------------------------------------------------------------------=
=2D------------------------------------------------------------------------=
=2D----------------
 Limit  (cost=3D0.00..0.04 rows=3D1 width=3D12) (actual time=3D0.046..0.048=
 rows=3D1=20
loops=3D1)
   ->  Index Scan Backward using origo_person_created_idx on onp_crm_person=
 p =20
(cost=3D0.00..8396.45 rows=3D200819 width=3D12) (actual time=3D0.041..0.041=
 rows=3D1=20
loops=3D1)
 Total runtime: 0.104 ms
(3 rows)

Is it possible to use some sort of "magic" function to get this number out =
as=20
a separate column? And is this number accurate? It has to be the same as=20
running a separate "count(*)"-query to count the totals, which is exactly=20
what I'm trying to avoid.

Oracle has a special rownum and over() which can be used to accomplish this:

SELECT tmp.*, max(rownum) over() as total_count
 FROM (subquery) tmp

Does PG have any equivalent way?

=2D-=20
Andreas Joseph Krogh <andreak@officenet.no>
Senior Software Developer / Manager
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