From 52d095ec16df05f3969f19e0c4df802987228b67 Mon Sep 17 00:00:00 2001 From: Sandro Santilli Date: Wed, 16 Feb 2011 11:15:59 +0000 Subject: [PATCH] Document ST_UnaryUnion git-svn-id: http://svn.osgeo.org/postgis/trunk@6830 b70326c6-7e19-0410-871a-916f4a2858ee --- doc/reference_processing.xml | 62 +++++++++++++++++++++++++++++++++++- 1 file changed, 61 insertions(+), 1 deletion(-) diff --git a/doc/reference_processing.xml b/doc/reference_processing.xml index 228d6bfb2..568209939 100644 --- a/doc/reference_processing.xml +++ b/doc/reference_processing.xml @@ -2496,9 +2496,69 @@ MULTILINESTRING((3 4,4 5),(1 2,3 4)) See Also - + + + + + + + + + + ST_UnaryUnion + + Like ST_Union, but working at the geometry component level. + + + + + + geometry ST_UnaryUnion + geometry geom + + + + + + + Description + + + Unlike ST_Union, ST_UnaryUnion does dissolve boundaries + between components of a multipolygon (invalid) + and does perform union between the components of a + geometrycollection. + Each components of the input geometry is assumed to be + valid, so you won't get a valid multipolygon out of a + bow-tie polygon (invalid). + + + + You may use this function to node a set of linestrings. + You may mix ST_UnaryUnion with ST_Collect to fine-tune + how many geometries at once you want to dissolve to + be nice on both memory size and CPU time, finding the + balance between ST_Union and ST_MemUnion. + + + &Z_support; + + Availability: 2.0.0 - requires GEOS >= 3.3.0. + + + + + + See Also + + + + + + + -- 2.50.1