[mapserver-dev] Implement getNumFeatures for some drivers

[Lime, Steve D (MNIT)]

A filter is basically a where statement so I think it should be considered...
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From: mapserver-dev <mapserver-dev-bounces at lists.osgeo.org> on behalf of Tamas Szekeres <szekerest at gmail.com>
Sent: Sunday, April 22, 2018 2:36:44 PM
To: mapserver-dev at lists.osgeo.org
Subject: [mapserver-dev] Implement getNumFeatures for some drivers

Hi Devs,

Currently getNumFeatures is supported by the inline layers only. Would that be sufficient to implement this for some other drivers, like  MSSQL, PostGIS and OGR?

The database drivers would probably rely on the count() aggegate in the SQL query, while we could use  OGR_L_GetFeatureCount for the OGR layers.

I could also imagine a default implementation if we use whichShapes on the layer extent and iterate the shapes to calculate the count.

It is also a question whether getNumFeatures should consider the layer filter or not.

Best regards,

Tamas

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