GML download slow through postgis compared to local shapefiles

[Maarten Plieger]

Hi All,
 >Patricio Cifuentes Ithal schreef:

> Hi,
> Test with "the_geom from table using SRID=4326"

I tested this with the statement above and the results are:
WMS request: 3.3 seconds
WFS request: 215 seconds
66.8 MB in 3 min 35 sec
312 Kb/sec
This is slower than the previous timings.

> Bart wrote:
> dit komt omdat Mapserver per feature 1 SQL statement af zal vuren op 
> PostGIS ....

I believe this is indeed the case. But for the WMS request, the response 
is much quicker from postgis. You can view all the data in 3.3 seconds. 
I guess with the WMS request all the data is transfered at once, using 
one statement?
Is it possible that this could be made for the WFS request too? Or that 
it is possbible to request more than one feature for each SQL statement? 
It would be really nice to see the GML download speed up.
Regards,
Maarten Plieger






>> -----Mensaje original-----
>> De: UMN MapServer Users List [mailto:MAPSERVER-USERS at LISTS.UMN.EDU] En
>> nombre de Maarten Plieger
>> Enviado el: Jueves, 25 de Octubre de 2007 12:57
>> Para: MAPSERVER-USERS at LISTS.UMN.EDU
>> Asunto: [UMN_MAPSERVER-USERS] GML download slow through postgis
>> compared to local shapefiles
>>
>> Hello All,
>> Currently I am comparing GML download performance through a WFS with
>> mapserver. The source data is stored directly on disk in the ESRI shape
>> format, and is also available from a postgis database located on the
>> same machine. So it is exactly the same data but from different
>> sources.
>> The shapefiles contain about 90000 polygons per file. I am timing the
>> rendering time in WMS and the download speed in WFS.
>> WMS rendering time for a shapefile:
>>     For the shapefiles on disk:  2.897 seconds
>>     From the postgis database: 3.3 seconds.
>> (seems ok for both data sources)
>>
>> However when I start downloading the data with the WFS in GML2 format:
>> For the shapefiles on disk:  8 Seconds
>>     66,8 MB in 8 sec
>>     8,35 Mb/Sec <== fast
>>  From the postgis database: 84 Seconds
>>     66.8 MB  in 1 min 24 sec
>>     800KB/Sec <== slow
>>
>> These are the postgis parameters:
>> CONNECTIONTYPE postgis
>> CONNECTION "host=localhost dbname=pliegerdatabase user=plieger
>> password=* port=5432"
>> DATA "the_geom from (select * from vcdtrop) as foo using unique gid
>> using SRID=4326"
>>
>>     
> [Patricio Cifuentes Ithal]
> Hi,
> Test with "the_geom from table using SRID=4326"
>
>
>
>
>  
>> Why is downloading GML data through WFS from a postgis database 10
>> times
>> slower than from locally stored shapefiles?
>> Can I do something to improve things? I am using mapserver 5.0.0-rc1 on
>> SUSE.
>>
>> Thanks in advance,
>> Maarten Plieger
>>
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