map performance

[Steve Lime]

Might be interesting to see what the resulting mapfile (after your
dynamic work) looks like (use $map->save(...)).

We'd really need to know more about the data, how you're doing
classifications and such to comment more. There may be lots of ways
to make things go faster. From the looks of it for each geography
(city, county, tribe, state, nation) you have a bunch of variables that
indicate
if a data theme is available. One could organize that data like so (for
example state level data):

State  Hydrography  Watersheds ...
MN     0                    1 
WI      3                    2
IA       3                    0
FL       1                    3

Where 0 means no responce, 1 complete and so on. So in that case your
class definitions would always be the same you'd
be simply changing the variable you're mapping on (e.g. CLASSITEM), and
you wouldn't need dynamic classes (or even MapScript for that
matter).  Just thinking out loud...

Steve

>>> boice tomlin <boice at RUNSKIP.COM> 12/4/2006 1:24:58 PM >>>

Hello users,

The map located here;

http://gisinventory.net/status_maps.html 

takes a while to load.  At least at the national view where there is a
lot of area to render.

I am looking for alternative ways to generate the map that will
significantly improve performance.

Currently I am using php and looping through data and turning on layers
as I go.  The PHP part is lightning fast.  But after I get the map ready
mapserver takes several seconds to generate it.

I'm curious about alternative ways to handle this problem and wonder if
anyone had comments on any of them.

1) modifying the shape files in some way so the layer information is in
those files so that all mapserver has to do is load those files and not
depend on the map files.
2) using a db such as postgres with postgis so that layer information
is available all in one compact source.

Right now I have to generate a bunch of dynamic classes in PHP using
the general method below.

$lyr = $this->ramona_map->getLayerByName("state_yes");
                $cla = $lyr->getClass(0);
                $cla->setExpression("/".$expression."/");
                $lyr->set("status", MS_ON);

I have to do this several hundred times to represent all of the data. 
The time it takes to generate the map seem proportionate to the amount
of layers I make visible.  And again this is on the mapserver side and
not PHP.  PHP does its part of the operation in thousandths of a
second.

anyone's thoughts are greatly appreciated.

-boice tomlin



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