[postgis-users] Topology: error creating aggregated topogeom (at city level) from a neighborhoods topogeom

Sandro Santilli strk at keybit.net
Mon Feb 1 07:04:45 PST 2016

On Mon, Feb 01, 2016 at 11:03:14AM -0200, Lucas Ferreira Mation wrote:

> >Here you're trying to pass a "layer_id" as the "type" of component for a non-hierarchical layer, thus the error

> *TopoElementArray_Agg(ARRAY[(tg_geom_dump_utm).id,(tg_geom_dump_utm).layer_id])*
> works.

Yes, that's how you're supposed to use it.

> What is not very clear from the syntax is if the syntax of
> *TopoElementArray_Agg
> should follow the child or the parent topogeom "class" (hierarquical or not)

It's TopoElement that matters, TopoElementArray_Agg is just an
aggregate to collect a set of TopoElement objects.

TopoElement is documented here:

"second element represents layer identifier of the child TopoGeometry"

> To recap, this is the code that works:

Consider adding it to the PostGIS Wiki !

This may be a good starting point:


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