From: Markus Schaber <schabi@logix-tt.com>
To: PostGIS Users Discussion <postgis-users@postgis.refractions.net>
To: PostgreSQL SQL List <pgsql-sql@postgresql.org>
Subject: Problem using set-returning functions
Date: Mon, 27 Mar 2006 12:41:32 +0200
Message-ID: <4427C15C.5070905@logix-tt.com> (raw)
In-Reply-To: <4427BFE4.8050500@logix-tt.com>
References: <20060324200036.ED8E52C1503@netnation.refractions.net>
<1143278826.44250cea7eccc@web-mail1.uibk.ac.at>
<4427BFE4.8050500@logix-tt.com>
Hi,
I'm cross-posting this to the plpgsql list:
We've run into a small problem creating a set-returning function for
PostGIS in PostgreSQL 8.1.0:
CREATE OR REPLACE FUNCTION generate_x (geom geometry)
RETURNS SETOF double precision AS
'DECLARE
index integer;
BEGIN
FOR index IN 1 .. npoints(geom) LOOP
RETURN NEXT X(geometryn(geom,index));
END LOOP;
END
' LANGUAGE 'plpgsql' IMMUTABLE STRICT;
Now, trying to use this function yields the following error:
navteq=# select foo,generate_x(bar) from test;
ERROR: set-valued function called in context that cannot accept a set
CONTEXT: PL/pgSQL function "generate_x" line 5 at return next
However, it is fine to call other set returning functions in the same
context:
navteq=# select foo,dump(bar) from test;
foo | dump
-----+--------------------------------------------------
42 | ({1},0101000000000000000000F03F0000000000000040)
42 | ({2},010100000000000000000008400000000000001040)
42 | ({3},010100000000000000000014400000000000001840)
23 | ({1},01010000000000000000001C400000000000002040)
(4 rows)
navteq=# select foo,x(geometryn(bar,generate_series(1,npoints(bar))))
FROM test;
foo | x
-----+---
42 | 1
42 | 3
42 | 5
23 | 7
(4 rows)
(This third query is equal to what I expected the failing query to do.)
The table "test" looks as follows;
navteq=# \d test
Table "public.test"
Column | Type | Modifiers
--------+----------+-----------
foo | integer |
bar | geometry |
navteq=# select foo,asText(bar) from test;
foo | astext
-----+-------------------------
42 | MULTIPOINT(1 2,3 4,5 6)
23 | MULTIPOINT(7 8)
(2 rows)
I'm shure its a small detail I've blindly ignored, but I'm stuck ATM.
Thanks,
Markus
--
Markus Schaber | Logical Tracking&Tracing International AG
Dipl. Inf. | Software Development GIS
Fight against software patents in EU! www.ffii.org www.nosoftwarepatents.org
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To: pgsql-sql@postgresql.org
Cc: schabi@logix-tt.com, postgis-users@postgis.refractions.net
Subject: Re: Problem using set-returning functions
In-Reply-To: <4427C15C.5070905@logix-tt.com>
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