[mapguide-dev] Enhanced Join Support RFC

[Jason Birch]

Overall, I like this proposal.  I think that the 1:many support is probably a good first step.  It makes it easier to query secondary data sources and return geometry.  
 
However, it is really just a right outer join, and does not provide for some of the most common map operations that will be required with 1:Many relationships.
 
In particular, it will not be able to support maptips (display all owners for a parcel), queries (only show properties with more than one service connection) and theming (color ramp based on number of calls for service)
 
I think that this would be best dealt with in two ways.  First, I would like to see an option to return a single geometry row, with a nested rowset representing the "Many" records.  Second, I would like to see the option to return a single geometry row along with some basic aggregate (sum, min, max, mean, group_concat) and search (contains) results, essentially acting as a GROUP BY operator on the root geometry.  These could even be combined, allowing both the aggregate functions and the nested results to be returned.  
 
I understand that this is a big request, but I thought I'd reiterate it here.  It was discussed in IRC after the last meeting, but I don't have the logs.
 
I also have a question about why spatial and aspatial data sources are so segregated in Studio.  I may just be a bit fuzzy, but is it possible to join a secondary table in an SDF file to a primary table in the same SDF file?  In another SDF file?
 
Jason

________________________________

From: Ronnie Louie
Sent: Fri 2006-11-03 2:48 PM
To: dev at mapguide.osgeo.org
Subject: [mapguide-dev] Enhanced Join Support RFC



Hi All,

 

A first draft of Enhanced Join Support RFC for MGOS is posted at http://wiki.osgeo.org/index.php/MapGuide_RFC_5_-_Enhanced_Join_Support.

 

Please have a look and post your feedback to this group.

 

Thanks

Ronnie Louie

 

 

 

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