[postgis-devel] Xing Lin's SoC project (raster support)

Paul Ramsey pramsey at refractions.net
Wed Jul 11 13:06:21 PDT 2007

Or, if you want the encapsulation of "object in a row", and don't want a 
foreign key relation to traverse, use a composite type:



Paul Ramsey wrote:
> More specifically, there is a lot of talk about "user defined types" in 
> this document, but the model does not really require any -- the whole 
> thing can be done with relations.  Doing it as UDT's requires lots of 
> book-keeping code for accessors to the properties of the types, doing it 
> as relations does not.
> The same thing could be said about geometry, of course, but the 
> difference is that geometry objects have a unitary structure that only 
> makes sense in aggregate, so breaking them up is wasteful -- you have to 
> put them back together again before they are useful.
> This is less true of these georasters, and in fact they will be somewhat 
> broken up anyways, into bands, for example.  Why not start this process 
> by building the whole thing as a relational model and then see what 
> doesn't work well and needs a UDT for efficiency?
> P
> Paul Ramsey wrote:
>> I'm a little worried at the quantity of this document that is copied 
>> verbatim from the Oracle Georaster documentation.  I mean, are we just 
>> cribbing their whole design directly?  The Oracle model is pretty, but 
>> it breaks up the rasters into an internal relational model, which 
>> pretty much requires some sort of toolset for people to load/unload data.
>> Second, the documentation stops with the model, it provides no 
>> functions, or even hint of what functions will be done first. 
>> Providing objects and no functions, or no data loader, is going to be 
>> a pure Waste of Time. I know he's not going to have time to copy the 
>> complete set of Georaster functions from Oracle, so an idea of what 
>> functions he plans to do first is pretty important.
>> PostGIS 0.1 had the types, it had input/output methods, and it had 
>> index bindings.  If this implementation does not have a way of getting 
>> data in and out, it's not going to be worth the time putting it together.
>> P.
>> Tim Keitt wrote:
>>> I'm attaching a proposal to add raster support to postgis. This is
>>> Xing Lin's SoC project. I'm hoping to get feedback on the spec and
>>> ideas for additions, modifications. Implementation is underway, but
>>> its not too late to make changes if people see significant problems or
>>> have suggestions.
>>> Cheers,
>>> Tim
>>> ------------------------------------------------------------------------
>>> _______________________________________________
>>> postgis-devel mailing list
>>> postgis-devel at postgis.refractions.net
>>> http://postgis.refractions.net/mailman/listinfo/postgis-devel


   Paul Ramsey
   Refractions Research
   pramsey at refractions.net
   Phone: 250-383-3022
   Cell: 250-885-0632

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