Performance hints please

[Ed McNierney]

Stephen -

"The amount of geometry involved is so small, the bottleneck has to be
the raster processing"

That is a dangerous assumption.  Retrieving a small amount of data from
a large, slow database server can take a long time - particularly if
you're re-establishing the connection each time.

Are you using pooled persistent connections to PostGIS with a FastCGI
MapServer?

	- Ed

Ed McNierney
President and Chief Mapmaker
TopoZone.com / Maps a la carte, Inc.
73 Princeton Street, Suite 305
North Chelmsford, MA  01863
ed at topozone.com
(978) 251-4242  

-----Original Message-----
From: UMN MapServer Users List [mailto:MAPSERVER-USERS at LISTS.UMN.EDU] On
Behalf Of Stephen Davies
Sent: Thursday, April 06, 2006 4:04 AM
To: MAPSERVER-USERS at LISTS.UMN.EDU
Subject: [UMN_MAPSERVER-USERS] Performance hints please

G'day all.

Does anybody have a howto on Mapserver performance enhancement?

My particular environment of interest is a relatively small set of
geometries in a PostGIS database and a collection of geotiff aerial
photography images onto which I overlay the geometries.

The geometries are fully indexed, relatively static and vacuum analyzed
every night.

One of the options that users have is to request a "movie" of up to 20
frames; each of which consists of a background raster plus up to about
five circular geometries, about five points and maybe ten other
lines/polygons.

The amount of geometry involved is so small, the bottleneck has to be
the raster processing. The images are 2m/pixel and are typically 20 -
150 Mb each. The frame extents include most if not all of an image so
tiling does not seem relevant.

I have specified 80% JPEG as the output to minimise final image size and
this seems successful (at least in terms of size and hence download
time)

I am looking for ways to reduce the time taken in the image generation
phase.

TIA,
Stephen Davies

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