Depending on the size of your structures, something like the below may
be significantly faster than the subselect alternative, and more
reliable than the ctid alternative.
CREATE TYPE result_info AS (a integer, b integer, c integer, d integer);
CREATE OR REPLACE FUNCTION parallelselect() RETURNS SETOF result_info AS
'
DECLARE res result_info%rowtype;
ct1_found boolean DEFAULT true; ct2_found boolean DEFAULT true;
ct1 CURSOR FOR SELECT a,b FROM t1; ct2 CURSOR FOR SELECT c,d FROM t2;
BEGIN
OPEN ct1; OPEN ct2;
LOOP
FETCH ct1 INTO res.a, res.b; ct1_found := FOUND;
FETCH ct2 INTO res.c, res.d; ct2_found := FOUND;
IF ct1_found OR ct2_found THEN RETURN NEXT res; ELSE EXIT; END IF;
END LOOP;
RETURN;
END;
' LANGUAGE plpgsql;
SELECT * FROM parallelselect() AS tab;a | b | c | d
---+---+---+---2 | 2 | 4 | 53 | 5 | 7 | 34 | 7 | 3 | 29 | 0 | 1 | 1 | | 2 | 0
(5 rows)
On Wed, 2004-08-11 at 10:11, David Garamond wrote:
> How can you display two tables side by side? Example:
>
> > select * from t1;
> a | b
> ---+---
> 2 | 2
> 3 | 5
> 4 | 7
> 9 | 0
>
> > select * from t2;
> c | d
> ---+---
> 4 | 5
> 7 | 3
> 3 | 2
> 1 | 1
> 2 | 0
>
> Intended output:
> a | b | c | d
> ---+---+---+---
> 2 | 2 | 4 | 5
> 3 | 5 | 7 | 3
> 4 | 7 | 3 | 2
> 9 | 0 | 1 | 1
> | | 2 | 0
>
> Each table has no keys (and no OIDs). Order is not important, but each
> row from each table needs to be displayed exactly once.
>
> --
> dave
>
>
> ---------------------------(end of broadcast)---------------------------
> TIP 4: Don't 'kill -9' the postmaster