[postgis-users] topology example

[Sandro Santilli]

On Fri, Feb 24, 2012 at 01:52:44PM +0100, Denis Rouzaud wrote:
> To be sure, we understand each others, here is the few lines of SQL
> I am using:
> https://github.com/3nids/qWat/blob/7bc65b5a43ffb9ae5947ede683ff1f2274807972/sql/topology.sql

It seems good to me. Do I read it correctly that it exits
the loop on first error ?
May I suggest you ORDER BY id in the loop ?
Or the order would not be predictable.

> I know I have errors in topology in my pipes. So, is this correct
> than I can use toTopoGeom for geometries that have incorrect
> topology?

Well, they should be fine for the population of primitives,
may give problems in the mapping between original features
and topology primitives. In any case the exception you got
doesn't reveal such problem.

> Here is the result of validate topology when a part of my pipes is
> in the topology column:
> SELECT topology.ValidateTopology('distrib_topo');
>      validatetopology
> ---------------------------
>  ("face without edges",0,)
> (1 row)

Uhm, that's a false positive, I tought I fixed it.
Evidently I didn't. Want to file a ticket about it ?

> I can dump the db, this will be a few megas, but I would like to be
> sure I am not doing anything stupid, first....

It would help me as well if you reduce it.
The important thing is that insertion of your offending geometry
keeps hitting the exception.
You could for example try dropping edges and then nodes
which do not intersect the offending geometry's bounding box.
And see if the problem still occurs.

Best to backup the whole set first.

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