[postgis-users] srid of columns in views

Vortex vortex25 at gmx.de
Sun Apr 24 04:37:57 PDT 2005


Thank you for your quick answer!

> The SRID is included in *every* geometry object, where its absence
> means a SRID of -1, which is *unknown*.
> The srid() function fetches this "embedded" value.
That's interesting. Indeed, the srid of table stored
geometrys seems to stay, even if i change the srid
in geometry_columns. (of course only if i use srid())
So the value in geometry_columns is for informational
purposes only and for the check constraints?

> DATA "the_geom from view using SRID=4326
Ok, but this is done by the mapserver, not by the
postgis extension?

> Read Mapserver manual for deeper info.
Will do :-).

> About the queries you show below I can't really understand them:
> what's "path" in geo_links ? If it's a projection of the real 
> data the srid() function should return the same result for both..
I've discovered the Problem until now. "path" in geo_links is
the calculated propagation path between two stations in a real
table. This calculation is done by the view itself. Unfortunately
i've done this wrong, so the path geometry comes out of the
view with a wrong srid althought it was correct defined in
geometry_columns.
With your explanations it was'nt difficult to find and fix this
Problem. It isn't surprising, that the query failed.

Thank you very much!
Klaus

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