MySQL Bugs: #53743: union, intersection functions to work on multiple geometries

Bug #53743	union, intersection functions to work on multiple geometries
Submitted:	18 May 2010 10:11
Reporter:	John Powell	Email Updates:
Status:	Open	Impact on me:	None
Category:	MySQL Server: GIS	Severity:	S4 (Feature request)
Version:	Any	OS:	Any
Assigned to:	Assigned Account	CPU Architecture:	Any
Tags:	gis, intersection, spatial, UNION

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Description:
The union and intersection functions currently only work with 2 arguments, ie, select union(geom1, geom2)
For a lot of GIS analysis, it is useful to be able to combine features based on some attribute, for example,

select union(geom),attribute from sometable group by attribute

or simply

select union(geom) from sometable

Ideally, the output should be polygon and not multipolygon -- any set of unioned/intersected polygons sharing an attribute, but which are spatially non-continguous should be output as a separate tuple, not as a multipolygon. 

How to repeat:
N/A as feature request.