Changes between Version 78 and Version 79 of WKTRaster/SpecificationWorking01

Timestamp:

Dec 18, 2009, 9:46:54 AM (14 years ago)

Author:

pracine

Comment:

—

WKTRaster/SpecificationWorking01

@@ -261 +261 @@
  This function construct the WKT strings representing the geometries grouping pixels of a raster having the same value. It does not directly construct geometries and therefore prevent WKT Raster from having to link with liblwgeom.a (see "Why avoid to link with PostGIS?" below) It should also return the value associated with this WKT polygon.
 
- Ways for a pg/plSQL function to return many columns:
+ Ways for a pg/plSQL or SQL function to return many columns:
 
  Functions with Output Parameters (PgSQL doc 34.4.3):
 
- CREATE FUNCTION sum_n_product (x int, y int, OUT sum int, OUT product int)[[BR]]
+ CREATE FUNCTION sum_n_product(x int, y int, OUT sum int, OUT product int)[[BR]]
  AS 'SELECT $1 + $2, $1 * $2'[[BR]]
  LANGUAGE SQL;
 
- Ways for a pg/plSQL function to return many rows:
+ The function must be called in the FROM clause, otherwise it returns a 
+ 
+ SELECT * FROM sum_n_product(11,42);
+
+
+ Ways for a pg/plSQL or SQL function to return many rows:
 
  It should be implemented by passing the raster to GDAL and convert each polygon produced by the [http://www.gdal.org/gdal__alg_8h.html GDALPolygonize function] to a WKT string.