map performance

[Ed McNierney]

Boice -

I want to make sure you realize that your "PHP work" is really doing
nothing more than creating the data structures to be used in rendering
your map.  It's not reading any shapefiles, drawing output images, etc.
- it's just looping and creating instructions for the "draw" method to
follow.  The fact that it happens "really fast" is both unsurprising and
unimportant.

It's as if you were running a program to generate instructions for
yourself to follow; generating a list that says "scratch your ear" 500
times is fast to generate and (relatively) fast to perform, but
generating a list that says "fly to Patagonia" 500 times is equally fast
to generate but enormously slower to perform.

Your fast code is simply generating the list.  The map-drawing is doing
the work of following the instructions, so Steve's suggestion is still a
good one.  If you can use the $map->save() method and post the results,
then we can see what the instructions are.

     - Ed

Ed McNierney
President and Chief Mapmaker
TopoZone.com / Maps a la carte, Inc.
73 Princeton Street, Suite 305
North Chelmsford, MA  01863
Phone: +1 (978) 251-4242
Fax: +1 (978) 251-1396
ed at topozone.com

-----Original Message-----
From: UMN MapServer Users List [mailto:MAPSERVER-USERS at LISTS.UMN.EDU] On
Behalf Of Boice Tomlin
Sent: Tuesday, December 05, 2006 10:52 PM
To: MAPSERVER-USERS at LISTS.UMN.EDU
Subject: Re: [UMN_MAPSERVER-USERS] map performance

Thanks Steve,

I will save the map file and take a look.  great tip.

In my case I have a few layers which are always on because I know the
get displayed on every request.  For instance I have on layer called
county. 
Every contry rendered on the map is from that single layer.

What I do is grab all county data that are complete(a user has complete
data for the chosen layer in that geography) - green - and form a long
regular expression with all thouse counties.  Then I form a class
dynamically and set the color to green.

Then I do the same thing for in-progress data, form a regular expression
from several hundred results, create a class from that same county layer
and set the color to orange.

I'm not sure Steve if I'm hearing you right.  You may be referring to a
completely different method that I'm not getting.  The thing is that the
PHP work described above happens fast, really fast.

The amount of time the maps takes to render is proportionate to the
amount of counties, cities, etc. in my regular expression.

does that make my situation clearer.

thank you for your help,

boice



> 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
>
>
>
> ////////////////////////////
> Run Skip
> http://runskip.com/
>
>
> boice tomlin
>
>
> boice at runskip.com
>
>
> 503-528-6204
>



////////////////////////////
Run Skip

boice tomlin

boice at runskip.com

503-528-6204