Changes between Version 3 and Version 4 of UsersWikiCascadeUnion


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Timestamp:
04/15/09 12:53:53 (16 years ago)
Author:
robe
Comment:

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  • UsersWikiCascadeUnion

    v3 v4  
    55for the current PostGIS ST_Union aggregate function.  It should work in PostGIS versions
    661.2.2 -- 1.3.4.  Although I have only tested on 1.3.3 and 1.3.4SVN.  Seems to work in general 5-10 times faster than built in ST_Union, but I haven't really hammered it to ensure
    7 it achieves the desired result in all cases.
     7it achieves the desired result in all cases. '''NOTE: For PostGIS 1.4 with GEOS 3.1.0 this is not necessary since cascaded Union is built into GEOS 3.1+ and PostGIS 1.4+ can take advantage of it '''
    88
    99In general I have found it to be 5-10 times faster than the built-in ST_Union aggregate function and also it finishes to completion in many cases where the built-in one runs out of memory.