OGR ODBC spatial query has invalid resultset
Jacob.Delfos at MAUNSELL.COM
Tue Sep 26 19:57:38 EDT 2006
Thanks a lot for that. It works great. That's really saved my neck.
> -----Original Message-----
> From: Frank Warmerdam [mailto:warmerdam at pobox.com]
> Sent: 26 September 2006 21:08
> To: Delfos, Jacob
> Cc: MAPSERVER-USERS at LISTS.UMN.EDU
> Subject: Re: [UMN_MAPSERVER-USERS] OGR ODBC spatial query has
> invalid resultset
> Delfos, Jacob wrote:
> > Hi List,
> > Sorry about all the questions I have been sending. I'm
> hoping someone
> > can shed light on this one.
> > After a QueryByPoint or QueryByRect operation in PHP, the number of
> > results is correct, but the resultCacheMemberObj always
> points to the
> > first "getNumResults()" objects. If there are 4 results, it holds
> > references to objects 1-4. For one result, it always points
> to the 1st
> > object.
> > This is -not- the case for QueryByAttributes, though. The
> > resultCacheMemberObj is correct for this type of query.
> > This only occurs for OGR ODBC layers. I have tried MDB and
> CSV, with the
> > same problem...
> > If anyone knows why, please let me know. If someone thinks
> this is a
> > bug, I'll file it.
> This occurs with OGR ODBC datasources that lack an FID column
> in the original
> table. Without an FID, OGR just assigns FIDs starting with
> zero to the
> result set.
> The problem really bites when different constraints (spatial
> or attribute)
> are in place at the point where the query is done, and when
> the results are
> fetched - which is the case when you do spatial queries as
> the spatial query
> apparently is cleared by mapserver before it starts fetching
> The overall point is that two-stage queries (as done by mapserver) are
> very unreliable against OGR datasources without a persistent
> FID, such as
> some ODBC datasources.
> BTW, you can use the mapserver config variable ODBC_OGR_FID
> to force the
> ODBC driver to pick a particular column as the FID.
> Unfortunately this
> is a global option so it only works smoothly if you have the same name
> for the id of all tables you are accessing in a given
> mapserver map. You
> would add something like the following in the MAP section of
> your map file
> to default to using the ID column of your odbc tables as the
> feature id.
> CONFIG "ODBC_OGR_FID" "ID"
> Best regards,
> I set the clouds in motion - turn up | Frank Warmerdam,
> warmerdam at pobox.com
> light and sound - activate the windows | http://pobox.com/~warmerdam
> and watch the world go round - Rush | President OSGeo,
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