OGR virtual spatial data

[Kralidis,Tom [Burlington]]

Thanks Bart.  I'll upgrade to the GDAL 1.3.0 and test again.

As far as the ovf file syntax:

<OGRVRTDataSource>
    <OGRVRTLayer name="somelayer">
        <SrcDataSource>ODBC:u/p at foo</SrcDataSource>
        <SrcLayer>somelayer</SrcLayer>
        <GeometryType>wkbPoint</GeometryType>
        <LayerSRS>WGS84</LayerSRS>
        <GeometryField encoding="PointFromColumns" x="x" y="y"/>
    </OGRVRTLayer>
</OGRVRTDataSource>

So I'm assuming newer versions of GDAL will pass the spatial filter
(from WMS, mapserv CGI, shp2img -e etc.) and apply them to the WHERE
clause to emulate a bbox filter?

..Tom



> -----Original Message-----
> From: UMN MapServer Users List 
> [mailto:MAPSERVER-USERS at LISTS.UMN.EDU] On Behalf Of Bart van 
> den Eijnden
> Sent: Thursday, 08 September, 2005 02:03
> To: MAPSERVER-USERS at LISTS.UMN.EDU
> Subject: Re: [UMN_MAPSERVER-USERS] OGR virtual spatial data
> 
> 
> Tom,
> 
> this depends on your GDAL version. A few months ago Frank did 
> an enhancement for us which added the X and Y columns to the 
> WHERE clause. Before that, yes, all records were fetched.
> 
> Also, depending on your ovf file syntax, the driver might get 
> a list of all the tables in the database. I don't know if 
> your schema has many tables in there?
> 
> Best regards,
> Bart
> 
> Bart van den Eijnden
> Syncera IT Solutions
> Postbus 270
> 2600 AG  DELFT
> 
> tel.nr.: 015-7512436
> email: BEN at Syncera-ITSolutions.nl
> 
> >>> "Kralidis,Tom [Burlington]" <Tom.Kralidis at EC.GC.CA> 
> 09/08/05 1:13 am 
> >>> >>>
> Hi,
> 
> I have a MySQL table which I'm connecting to via OGR's 
> virtual spatial data option and unixODBC.  The table has ~ 2 
> million records with x and y columns.  I have setup an .ovf 
> and mapfile accordingly.
> 
> When I run shp2img, CPU usage spikes up to 100% and then a 
> core dump results.  I am running shp2img with an extent which 
> will result in far less records.
> 
> Any idea what's going on here?  Are all the records being 
> fetched BEFORE the spatial filtering by shp2img?
> 
> Thanks
> 
> ..Tom
> 
> =========================
> Tom Kralidis
> Senior Systems Scientist
> Environment Canada
> Tel: +01-905-336-4409
> http://www.ec.gc.ca/
>