[postgis-devel] Looking for a good ST_ChangeEdgeGeom semantic

[strk]

On Thu, Feb 16, 2012 at 08:48:38PM +0100, Andrea Peri wrote:

> If the starting situation was this:  (were 'o' are node not vertex)
> 
>     o--------------o
>     |              |
>     o------E1------o
>     |              |
>     |              |
>     |              |
>     o              o
>     |              |
>     |              |
>     |              |
>     o--------------o
> 
> 
> this other should be allowed with a ST_ChangeEdgeGeom ?
> 
>     o--------------o
>     |              |
>     o              o
>     |              |
>     |              |
>     |              |
>     o-----E1-------o
>     |              |
>     |              |
>     |              |
>     o--------------o
> 

This is explicitly forbidden by SQL/MM.
The new shape must have the same starting and ending nodes.

I think the rationale of this function is that you change the
shape attribute w/out modifying the topology as a whole.

--strk;

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