[postgis-users] Function of table "geometry_columns"

[Bart van den Eijnden]

The table geometry_columns is defined in the OGC Simple Features for SQL
spec.

It is a metadata table stating the name of the geometry column, the
geometry type, dimension, coordinate system etc.

It will depend on the actual application if it is really used, but it is
highly recommendable to keep it up to date, and for most cases PostGIS
will do this automatically.

But e.g. if you want to use a view in UMN Mapserver, you will need to
manually add it to the geometry_columns table.

Oid is an internal object identifier of the PostgreSQL database (a system
column), which is not used anymore automatically in PostgreSQL 8.1. UMN
Mapserver uses it as the default unique column for a table if you don't
another column with USING UNIQUE.

Hope this helps.

Best regards,
Bart

> Hello to all,
> I would like to know what the table "geometry_columns" is for.
> I work with UMN Mapserver and I have several geodata.
> Everything works really fine with postgis.:-)
> If I make a new table with geodata automatically an entry in the
> "geometry_columns" follows (with informations to SRID,type, etc.)
>  but I would like to know, if this is only a statistical table or if it is
> absolutely necessary?
> I also would like to knwo, what the oid in "geometry_columns" wants to
> tell
> me?
> Thank you very much.
> Kai
>
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