[gdal-dev] Call for discussion on RFC 92 text: WKB Only geometries

[Even Rouault]

Hi Seth,

Le 31/01/2023 à 14:20, Seth G a écrit :
> Hi Even,
>
> Is it correct to say the workflow for OGR layer in MapServer is similar to that of QGIS?
Not quite, because currently MapServer as you point out use 
"materialized geometries" to get the points, the number of rings in a 
polygons, etc.
> Would using WKB here be any more performant?
In the general case where the geometries in the datasource aren't 
encoding using WKB, probably not because you would have to pay for the 
WKB serialization & deserialization. It could, perhaps, help, a bit, for 
GeoPackage. To get the best performance, you'd need to have 2 code 
paths: one for OGR materialized geometry (the current one), and another 
one for OGR WKBOnly geometries.
> The PostGIS driver already has code to convert from WKB to shape [2] which could be repurposed.

Yes, if that was done, reusing the WKB -> msShapeObj converter from the 
PostGIS connector would be the way to go

Even

>
> Seth
>
> [1] https://github.com/MapServer/MapServer/blob/f3f05d4cf30af615d5f443a1c47c20b6117e52cb/mapogr.cpp#L250
> [2] https://github.com/MapServer/MapServer/blob/f3f05d4cf30af615d5f443a1c47c20b6117e52cb/mappostgis.cpp#L663
>
> --
> web:https://geographika.net
> twitter: @geographika
>
> On Tue, Jan 31, 2023, at 12:27 PM, Even Rouault wrote:
>> Hi,
>>
>> Please find for review "RFC 92 text: WKB Only geometries" at
>> https://github.com/OSGeo/gdal/pull/7149
>>
>> This RFC provides shortcuts to avoid instantiation of full OGRGeometry
>> instances
>> in scenarios where only the WKB representation of geometries is needed. The
>> hope is to save CPU time.
>>
>> This is something I wanted to at least experiment. I've mixed feelings
>> if it's something we actually want to adopt.
>>
>> Even
>>
>> -- 
>> http://www.spatialys.com
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>>
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-- 
http://www.spatialys.com
My software is free, but my time generally not.