[mapserver-users] Tiled PNG doesn't work for WCS (and WMS)

[Frank Warmerdam]

Steve Lime wrote:
> Be interested to hear if the soon-to-be released MapServer 5.6 fares any better speedwise. 5.0.2
> is pretty darn old. -Steve

Folks,

I believe much of the performance problem is that some versions of
GDALOpen() do a scan of the whole directory as part of the file opening
process. In a directory, like Steven's, with 60000 tiles (120000 files!)
that becomes a significant performance problem.  I have suggested a
configuration item that might disable this depending on his version of
GDAL.

I also noted that Steven's tiles are 1500x1500 pngs which is a pretty
crappy thing to serve web maps from.  MapServer and GDAL essentially
need to completely decode each PNG touched by a map request.  To it's
credit I believe GeoServer does some smart caching that helps if there
is any locality of requests.

I've also briefed Steven on use of shptree to build a spatial index on
his spatial index.

Anyways, my point is that the performance issues are not necessarily at
the MapServer level.

Best regards,
-- 
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I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
light and sound - activate the windows | http://pobox.com/~warmerdam
and watch the world go round - Rush    | Geospatial Programmer for Rent