[mapserver-users] Re: Mapscript

[Rodrigo Cabral]

Hello all,

Well, I'll try to shed some light into this discussion, regarding the SDO
part. About the shape_id, there are a few alternatives for Oracle
Spatial, but it will depend on how I will provide support for the last
functions that are missing implementation in our MapServer-SDO interface.

In Oracle Spatial I can provide a shape_id by using a "rownum" request in
the SELECT statement. Therefore, it will give me numbered ids that could be
used for uniquely identifying each record. On the other hand, it's also very
common for the user to define a column which is the unique key for the
table, namely a GID. So it would be a matter of including in the mapfile
"DATA" definition the name of the shape_id column, like this:

DATA "shape_column FROM mytable" (as it's today)
DATA "shape_column,shape_id FROM mytable" (could be implemented)

But as I mentioned recently in another email, Oracle Spatial has a good set
of functions for performing spatial queries in the database. So, for the
time being, I'm using those functions instead of going through MapServer's
interface. I have 3 very good reasons why one should choose this approach.
Please check the following URL, which is an loong email on the subject.

http://mapserver.gis.umn.edu/wilma/mapserver-users/0201/msg00129.html

Rod.

----- Original Message -----
From: "Daniel Morissette" <morissette at dmsolutions.ca>
To: "Jim Burnett" <jimburnett at ntelos.net>
Cc: "mapserver-users" <mapserver-users at lists.gis.umn.edu>
Sent: Friday, January 11, 2002 8:14 PM
Subject: Re: [mapserver-users] Re: Mapscript


Jim Burnett wrote:
>
> I've been looking into using getShap(), but doesnt it require the index of
> the shape? Not all databases will have this Index. I think you can get the
> shap via a class, but the shapeObj doesnt seem to work correctly. Do you
> have any sample code for drawing a shape, getting the shape by class, not
by
> the shape index?
>

I think I see what you mean: reocrds obtained from a RDBMS won't carry a
unique shape_id the same way as shapefiles and other file-based formats
will.  So you don't have any shape_id to pass to getShape() after a
query.  I don't know about SDE and PostGIS, but I have used SDO before
(outside of the MapServer world) and I believe that there is nothing in
OracleSpatial that can easily be mapped to a shape_id.

I guess the best ones to answer this question are the developers of the
SDO, SDE, and/or PostGIS connections:  Do the database-based connections
in MapServer have any equivalent of a shape_id?  If not then what should
one do to retrieve the shapes returned by a queryByPoint() in MapScript
for instance?

--
------------------------------------------------------------
 Daniel Morissette               morissette at dmsolutions.ca
 DM Solutions Group              http://www.dmsolutions.ca/
------------------------------------------------------------
  Don't put for tomorrow what you can do today, because if
      you enjoy it today you can do it again tomorrow.