[postgis-users] Anti st_union

[Simon Greener]

Bob,

> In order to have only one row, I have a number of points  stored in a table as st_union.

I assume you mean stored in a table as a MULTIPOINT geometry?

> Is there a method of breaking the points out of  the st_union geometry so that I can access the points individually.
>
> I want to use the points as a reference for st_within. It doesn't seem to works as it seems to regard the st_union point geometry as a whole.

Here is an example of what I think you want using 10 points dynamically generated, unioned and then Dumped.

select (ST_Dump(MPoint)).geom as Point
   from (select ST_Union(ST_Point(g.*,g.*)) as MPoint
           from generate_series(1,10,1) g
        ) as m;

Or

select ST_GeometryN(f.MPoint,f.pcount) as Point
   from (select m.MPoint, generate_series(1,ST_NumGeometries(m.mpoint),1) as pcount
           from (select ST_Union(ST_Point(p.*,p.*)) as MPoint from generate_series(1,10,1) as p ) m
        ) as f;

regards
Simon
-- 
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