EPSG lookup done for all layers

[banders@…]

For each WMS GetMap? request, Mapserver appears to fully resolve all projection definitions in the .map file, even for layers that aren't involved in the GetMap? request.

This isn't a huge problem when projections are fully defined within each .map file layer. But when using "init=EPSG" syntax, Mapserver will go to the Proj "epsg" file once for each layer.

The issue is speed. My experiments have shown that this slows down GetMap? responses by a few hundred milliseconds to a few seconds (depending on the number of layers and the placement of the projection definition within the "epsg" file.

Possible solutions:

a) only resolve EPSG codes for layers that are involved in the current map request

b) cache the projection definitions, so we don't need to go to the "epsg" file for every layer

[warmerdam]

Daniel,

Did you mention you were going to work on optimizing proj.4 projection lookups for mapserver?

[dmorissette]

Yes, this is one of the things I would like to do for 5.0... let's see if I'll have time to do it by the feature freeze date.

[dmorissette]

There is already ticket #1976 addressing this. Closing as duplicate.