MS_MAXLAYERS Question

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MS_MAXLAYERS Question

Ben Tuttle
Hi all-
We have a need to up MS_MAXLAYERS, we need to have large numbers of
layers in our mapfiles. We are thinking perhaps as high as 8000. Does
anyone have any thoughts on problems we might encounter by doing this
or other things we need to change at the same time? Are there any
other compile time contants that should be increased at the same time
as MS_MAXLAYERS?
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Re: MS_MAXLAYERS Question

Frank Warmerdam
On 12/15/06, Ben Tuttle <[hidden email]> wrote:
> Hi all-
> We have a need to up MS_MAXLAYERS, we need to have large numbers of
> layers in our mapfiles. We are thinking perhaps as high as 8000. Does
> anyone have any thoughts on problems we might encounter by doing this
> or other things we need to change at the same time? Are there any
> other compile time contants that should be increased at the same time
> as MS_MAXLAYERS?

Ben,

I think you will see parsing of the .map file become a dominant
cost with this many layers.  i really suspect you should either be
looking at some sort of tileindex based approach or using
mapscript to dynamic create the layers needed for a given request.

Best regards,


--
---------------------------------------+--------------------------------------
I set the clouds in motion - turn up   | Frank Warmerdam, [hidden email]
light and sound - activate the windows | http://pobox.com/~warmerdam
and watch the world go round - Rush    | Geospatial Programmer for Rent
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Re: MS_MAXLAYERS Question

Ben Tuttle
Thnaks for the info Frank. I hadn't considered dynamically creating
the layers, but that sounds promising. Can you give me an idea of a
number we might be able to increase MS_MAXLAYERS to that would not be
too much of a drain on the system?
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Re: MS_MAXLAYERS Question

Frank Warmerdam
On 12/15/06, Ben Tuttle <[hidden email]> wrote:
> Thnaks for the info Frank. I hadn't considered dynamically creating
> the layers, but that sounds promising. Can you give me an idea of a
> number we might be able to increase MS_MAXLAYERS to that would not be
> too much of a drain on the system?

Ben,

It depends on the complexity of the layer definition and
the kinds of objects that have to get created.  For instance
currently epsg lookups are quite expensive, so if every
layer had an epsg definition even 100 layers could be
quite slow.

I haven't really done any benchmarking so I can offer
detailed information ... just a the general sort of warning.

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