[Mapserver-users] PostGIS subselect & where'd the data go?

[Charlton Purvis]

Thanks, Jan.  I understand what you're saying, but by the same
reasoning, why DOES
  DATA "the_geom from se_bethy"
return all the fields?  After all, the_geom is just a column.

I'm glad that you brought my attention to that detail, too, since I
might only be interested in returning only a subset of those columns.
What if for some reason I had 10 columns as part of my table where 3
were blobs w/ a large amount of binary data, and I was only interested
in the other 7 smaller integer columns?  If I were to leave the
"the_geom from se_bathy" alone, I sure would spend a lot of time
shipping data to MapServer that I would not need.

I guess my question is:  why isn't it only one way or the other instead
of like it seems to be now, something in the middle?

-----Original Message-----
From: Jan Hartmann [mailto:jhart at frw.uva.nl] 
Sent: Friday, April 25, 2003 10:56 AM
To: mapserver-users at lists.gis.umn.edu
Subject: Re: [Mapserver-users] PostGIS subselect & where'd the data go?

Charlton,

When you put an SQL request to PostGIS  using a table name, all fields 
in that table are automatically returned to MapServer, alongside the 
geometry field. That's why you see "dataset", "source", etc in the 
result, although you did not specify them in the DATA statement. In a 
subselect however, you have to request *every* field you need (including

oid).  There is no default set of fields in a subselect.

Jan

Charlton Purvis wrote:

>So here are the two cases that should have the same results but don't.
>
>// CONTROL (no subselecting)
>   $layerObj->set("data","the_geom from se_bathy");
>
>// The TEST case is when I run my .php w/ this, instead:
>   $layerObj->set("data","the_geom from "
>   . "(select oid, the_geom FROM se_bathy where 1=1) "
>   . "AS foo USING UNIQUE oid USING SRID=-1");
>  
>
...
...

>CONTROL results
># results = 739 from bathy_postgis
>Data fields: | gid | dataset | source | res | depth_ft | depth_m |
>depth_fa |
>
>TEST results
># results = 739 from bathy_postgis
>Data fields: | oid |
>  
>
Jan Hartmann
Department of Geography
University of Amsterdam
jhart at frw.uva.nl

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