[mapserver-users] Does wms_extent of a layer impact performance

[James_in_Utah]

Hi,
I'm deploying the USDA NAIP image set on two of our servers on a closed LAN
with about 20 users.  About half of the NAIP set on each server.  I'm also
running MapCache on one of the servers with the cache being stored on an
empty drive.  The NAIP set is divided up by states, and some of the states
have more than one projection, for instance, California is in NAD83 UTM Zone
10 and Zone 11.  I've created a layer for each state, and if the state has
more than one UTM Zone, then there is a layer for each of the zones.  So,
for California, I have CA_Zone10, and CA_Zone11 layers.  So I probably have
close to 100 layers representing all of CONUS.  Being lazy, I put the same
"wms_extent" in the METADATA portion of each layer.  The extent is large
enough to cover all of CONUS.  Will this cause performance issues?  All 100
odd USDA_NAIP layers have the same "wms_extent:.  Will that cause MapServer
to open each of the shape files looking for the requested bounding box?  

Also, I have all the NAIP layers on one server grouped into "USDA_NAIP", and
all the NAIP layers on the other server grouped into "USDA_NAIP2", and the
MapCache has added each of the these "Groups" as sources.  The users will
just have to select both NAIP layers in MapCache.  Is there some way to have
both "Groups" appear as one layer in MapCache?  Everything seems to be
working, although it does seem slow, with just me hitting it so far.  

I've include my two California layers below as examples.  Any suggestions on
optimizing this would be appreciated.  I'm using the latest dev release of
MS4W.
Thanks,
James



   LAYER
      NAME "CA_Zone10"
      GROUP "USDA_NAIP"
      METADATA
         "wms_title" "CA_Zone10"
         "wms_name" "CA_Zone10"
         #Extent for USA
         "wms_extent" "-1154717.71708742, 2635432.86320029,
3632346.10222763, 6578042.27294455"
         "wms_srs" "ESPG:26910"
         "wms_style" "Default"
         "wms_format" "image/png"
      END
      STATUS ON
      TYPE RASTER
      TILEINDEX "D:\\MapData\\USDANAIP\\ca\\Zone10.shp"
      TILEITEM "Location"
      PROJECTION
         "init=epsg:26910"   
      END
      MAXSCALEDENOM 1000000
   END

   LAYER
      NAME "CA_Zone11"
      GROUP "USDA_NAIP"
      METADATA
         "wms_title" "CA_Zone11"
         "wms_name" "CA_Zone11"
         #Extent for USA
         "wms_extent" "-1154717.71708742, 2635432.86320029,
3632346.10222763, 6578042.27294455"
         "wms_srs" "ESPG:26911"
         "wms_style" "Default"
         "wms_format" "image/png"
      END
      STATUS ON
      TYPE RASTER
      TILEINDEX "D:\\MapData\\USDANAIP\\ca\\Zone11.shp"
      TILEITEM "Location"
      PROJECTION
         "init=epsg:26911"   
      END
      MAXSCALEDENOM 1000000
   END








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