Topology - how edit node and edge vertex position

[Sandro Santilli]

On Thu, Sep 26, 2024 at 10:11:12PM +0200, Michal Seidl wrote:
> Hello,
> I am trying to figure out, what is correct way to edit position/coordinates
> of nodes and edge vertexes.
> 
> While updating edge vertexes can be achieved with function
> ST_ChangeEdgeGeom() by updating whole geometry.
> 
> If I try to update start or end point I get 'SQL/MM Spatial exception -
> start node not geometry start point' that is correct by checking the C code
> of function.
> 
> So how to change position of start or end point of edge? I would expect some
> function but I am not able to find it.

There's currently no function to do that, and no specification of
behavior of such a function in the ISO standard.

You'd currently need to add the new node, split the existing edge,
drop the edge portion you don't need, add a new edge from the split
node to the new node, heal the 2 edges.

If you use TopoGeometry objects for storing attributes you would
probably have an easier life by using toTopoGeom and clearTopoGeom
to replace the old definition with a new definition and remove unused
primitives at the end.o

--strk;