Hi Arnaud,
This is good question, and I'd be interested to know the answer. As a
gut reaction, I don't think it'll matter too much.
That said, there are several variables about this which will be specific
to your use case. The best general advice is probably to set up a way
to measure performance. GeoSolutions has free training materials which
document using JMeter for testing just like this:
https://geoserver.geo-solutions.it/edu/en/enterprise/jmeter.html.
Once you have a way to gather measurement, it might be worth reviewing
the general GeoServer documentation for some of the best practices about
deploying GeoServer in production:
http://docs.geoserver.org/stable/en/user/production/index.html. I'd
specifically call out Marlin; I'd strongly suggest verifying that it is
on via the GeoServer Status Page in the UI.
At this point, if you are using JMeter, you should be able to get an
idea how about various changes are affecting performance. Being able to
test two versions of the style should give you confidence in your final
choices. (You can also need nerdy about testing the different scale
denominator bits, etc, etc by making careful queries in JMeter.)
If you are still wondering about performance... the next step is diving
in with a profiler. I've used YourKit to learn how specific function
where working some complex SLDs. As a result of that, I was able to
write custom CQL functions to speed up things. (This last suggestion is
non-trivial.)
I hope that helps. If this is a business need, a number of companies
support GeoServer commercially (http://geoserver.org/support/).
Cheers,
Jim
On 6/1/2018 5:39 AM, Arnaud L. wrote:
Hi list
I'm wrinting a new style and I have to make choices between filters
and expressions. I was wondering which one would be more efficient in
terms of rendering performance : 2 rules with static style, or one
rule with dynamic style ?
One simple example would be (in ysld) :
Filter version, two rules :
rules:
- filter: ${railway = 'rail' AND tunnel <> 'yes'}
symbolizers:
- line:
stroke-color: '#999999'
rules:
- filter: ${railway = 'rail' AND tunnel = 'yes'}
symbolizers:
- line:
stroke-color: '#DDDDDD'
Expression version, one rule, expression in style :
rules:
- filter: ${railway = 'rail'}
symbolizers:
- line:
stroke-color: ${if_then_else(isNull(tunnel),'#999999','#DDDDDD')}
I have mixed feelings about both. I can write filter expressions more
easily because the syntax is simple, and I am not familiar with CQL.
But I like the compacity of the expression version better.
Thanks for your thoughts !
--
Arnaud
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http://geoserver.org/comm/userlist-guidelines.html
If you want to request a feature or an improvement, also see this:
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