[mapserver-users] Display performance

[P Kishor]

On Thu, Sep 2, 2010 at 3:28 PM, Chris Jackson <webturtles at gmail.com> wrote:
> Hi
>
> 20 secs is from turning the layer on in the interface.  The data is a model
> grid as polygons, the file size is about 40mb.  I agree 20secs is too long -
> I am a web developer in general and know users are fickle!  The other layers
> load v.quickly so happy in general with performance of smaller model grids.
>
> The same layer in an old arcgis server app loads a few secs quicker (from
> SDE rather than file) and we just accepted it was just 'one of those things'
> and deadlines got in the way - mmm...
>
> The app is living on a reasonable specced server living in a data centre and
> the old web app has been serving the offshore renewables industry fine for a
> couple of years or so, just have a need to move to an open source solution.
> I was trying to get a feel whether moving to PostGIS rather than local file
> will speed things up - I get the feeling it is marginal.


Databases, generally, will be slower than files. You don't go to a db
for speed. You go to a db for a bunch of other advantages it brings,
especially in a read-write environment.

Have you indexed your shapefiles? If not, create an index, and you
will be surprised how fast the result will be.

Additionally, if you can, try process as little as possible to do the
work requested. In other words, wasted CPU is wasted CPU, so try not
to do calculations that you are going to throw away anyway.

Well, first, index the shapefiles.



>
> Maybe I am missing another processing trick (admittedly I have done minimal
> work bar a spatial index).
>
> Thanks for the swift response.
> Chris
>
> On 2 September 2010 21:07, P Kishor <punk.kish at gmail.com> wrote:
>>
>> On Thu, Sep 2, 2010 at 3:03 PM, Chris Jackson <webturtles at gmail.com>
>> wrote:
>> > Steve
>> >
>> > That saves some work, but how long would you expect one that size to
>> > load?
>> > I have just realised (admittedly not looked at the data for a couple of
>> > years) that it is actually 170,000 records - takes about 20 secs to load
>> > -
>> > sound reasonable?
>>
>>
>> What does "to load" mean? Is 20 seconds the time elapsed from when the
>> user clicks on the browser to when the user sees the resulting image?
>>
>> You are ripping through 170K features and creating an image. 20
>> seconds seems like a lot. How big and complicated are those features?
>> How big is the shapefile, in physical size (MB, KB).
>>
>> What kind of computer are you using?
>>
>> What other processes are running?
>>
>> So many variables...
>>
>> in any case, if you have a web app, and you want your users to remain
>> interested in it, you probably will want to bring down the time "to
>> load" to sub-second, or, at the most a few seconds. You will also want
>> to consider multiple users -- acceptable performance with one user
>> might translate into horrendous performance with several concurrent
>> users.
>>
>>
>>
>>
>> >
>> > Chris
>> >
>> > On 2 September 2010 20:50, Lime, Steve D (DNR) <Steve.Lime at state.mn.us>
>> > wrote:
>> >>
>> >> That’s not that big a dataset. Probably faster from a local shapefile.
>> >>
>> >>
>> >>
>> >> Steve
>> >>
>> >>
>> >>
>> >> From: mapserver-users-bounces at lists.osgeo.org
>> >> [mailto:mapserver-users-bounces at lists.osgeo.org] On Behalf Of Chris
>> >> Jackson
>> >> Sent: Thursday, September 02, 2010 2:29 PM
>> >> To: mapserver-users at lists.osgeo.org
>> >> Subject: [mapserver-users] Display performance
>> >>
>> >>
>> >>
>> >> Hi
>> >>
>> >> I wondered if anyone knew if displaying a 50,000 polygon dataset would
>> >> be
>> >> significantly faster if called from a database rather than a spatially
>> >> indexed shapefile, or is it a similar overhead for both.
>> >> Thanks
>> >> Chris
>> >
>> > _______________________________________________
>> > mapserver-users mailing list
>> > mapserver-users at lists.osgeo.org
>> > http://lists.osgeo.org/mailman/listinfo/mapserver-users
>> >
>> >
>>
>>
>>
>> --
>> Puneet Kishor http://www.punkish.org
>> Carbon Model http://carbonmodel.org
>> Charter Member, Open Source Geospatial Foundation http://www.osgeo.org
>> Science Commons Fellow, http://sciencecommons.org/about/whoweare/kishor
>> Nelson Institute, UW-Madison http://www.nelson.wisc.edu
>> -----------------------------------------------------------------------
>> Assertions are politics; backing up assertions with evidence is science
>> =======================================================================
>
>



-- 
Puneet Kishor http://www.punkish.org
Carbon Model http://carbonmodel.org
Charter Member, Open Source Geospatial Foundation http://www.osgeo.org
Science Commons Fellow, http://sciencecommons.org/about/whoweare/kishor
Nelson Institute, UW-Madison http://www.nelson.wisc.edu
-----------------------------------------------------------------------
Assertions are politics; backing up assertions with evidence is science
=======================================================================