[Qgis-user] Qgis-server recompute always the layer bbox ?

[Andrea Peri]

Hi,

study-ing the qgis code, I see in the spatialite provider there is a
significative piece of code conditioned by
some
#IFDEF SPATIALITE_VERSION_GE_4_0_0

I don't see any option in cmake setting named like this.

Is this a missing ?

Thx,

A.



2014-02-14 10:54 GMT+01:00 Andrea Peri <aperi2007 at gmail.com>:

> Hi,
> thx I now start to understand better the question.
>
> Infact I'm using spatialite db. A 4.1.1 db spatialite.
> The spatialite db has an internal statistics table to perform a very fast
> resolution of the bboxes of single datasets.
>
> I always update it using the command:
>
> select UpdateLayerStatistics();
>
> But the problem is if the client really use that table.
>
> Infact I guess more probably the qgis-server don't ask to spatialite the
> box from this table, but instead do a more usual
> sql to retrieve is.
>
> Hi Sandro,
> do you know the right query to retrieve the bbox from the statistics table
> of spatialite 4.1.1 ?
>
> I guess suspect that qgis (because it like) to be more compatible with all
> the oldest (arcaic) version of spatialite, simply avoid to use this table.
> :)
>
> Many thx.
>
>
> Andrea.
>
>
>
> 2014-02-14 10:34 GMT+01:00 Marco Hugentobler <
> marco.hugentobler at sourcepole.ch>:
>
>  Hi Andrea, Giovanni
>>
>> QGIS Server doesn't calculate the bbox itself, but it queries the extent
>> from the layers. So it can be that certain providers calculate the bbox (of
>> course only if the layer / capabilities document is not cached).
>>
>> For a faster startup, having a persistent cache as Giovanni suggested
>> might help.
>>
>> Regards,
>> Marco
>>
>>
>> On 14.02.2014 10:18, G. Allegri wrote:
>>
>>
>>>  I don't understand why the qgis-server eed to calculate always the
>>> bbox.
>>> In the server project windows,
>>> qgis ask for the published bbox.
>>>  Why it don't use it as bbox rather than calculate it on every request ?
>>>
>>
>>  Marco, correct me if I'm wrong.
>> QGIS Server doesn't calculate the BBOX, it parses the layers extents from
>> the .qgs project and then combine them to obtain the entire BBOX.
>> The only operation it does is reprojecting the extents to WGS84 to create
>> the EX_GeographicBoundingBox element.
>>
>>  Anyway, in case the project advertises and extent, the combined extent
>> won't be calculated, so in your case this phase shouldn't be the
>> bottleneck...
>>
>>  giovanni
>>
>>
>>
>>
>>
>>>
>>>  The FastCGI don't help really.
>>> In a publishing environment every few hour the instances are restated to
>>> removed zombi process.
>>> This mean that every few hours the FastCGI are emptied and reloaded.
>>> A fastcgi environment mean to load 20 instances of QGIS-server and every
>>> of them do them own elaboration .
>>> As the bbox calculation for every layer.
>>>
>>> GASP.
>>> The start could ask about one hours and more.
>>>
>>>  Also another problem with the fastcig is that when
>>>  I change something on a project I need to restart to Web instances to
>>> dismiss the actual project and reload the new.
>>>
>>>  So every change in a qgis project need a restart of all proccess (20
>>> and so on in a fastcgi enviroment) every with a slow bbox calculation phase.
>>>
>>>  mmhh...
>>>
>>>  :/
>>>
>>>
>>>
>>> 2014-02-14 9:13 GMT+01:00 G. Allegri <giohappy at gmail.com>:
>>>
>>>>
>>>>
>>>>
>>>> 2014-02-14 Marco Hugentobler <marco.hugentobler at sourcepole.ch>:
>>>>
>>>>  Hi Andrea
>>>>>
>>>>>
>>>>> >I suspect that QS try always to recalc the box of every layer.
>>>>>
>>>>>  QGIS server caches layers (up to 100, but that can be enhanced using
>>>>> the environment variable MAX_CACHE_LAYERS).  Furthermore, the
>>>>> GetCapabilities documents are cached (so no recalculation if using
>>>>> FastCGI).
>>>>>
>>>>>
>>>>  Thanks Marco, you confirmed what I told Andrea.
>>>> It would be a good enhancement if caching could be done in a persitent
>>>> manner (out of memory). We could consider, in the future, to use memcache
>>>> or something similar.
>>>>
>>>>  giovanni
>>>>
>>>>  _______________________________________________
>>>> Qgis-user mailing list
>>>> Qgis-user at lists.osgeo.org
>>>> http://lists.osgeo.org/mailman/listinfo/qgis-user
>>>>
>>>
>>>
>>>
>>> --
>>> -----------------
>>> Andrea Peri
>>> . . . . . . . . .
>>> qwerty àèìòù
>>> -----------------
>>>
>>
>>
>>
>>  --
>> Giovanni Allegri
>> http://about.me/giovanniallegri
>> Twitter: https://twitter.com/_giohappy_
>> blog: http://blog.spaziogis.it
>> GEO+ geomatica in Italia http://bit.ly/GEOplus
>>
>>
>>
>> --
>> Dr. Marco Hugentobler
>> Sourcepole -  Linux & Open Source Solutions
>> Weberstrasse 5, CH-8004 Zürich, Switzerlandmarco.hugentobler at sourcepole.ch http://www.sourcepole.ch
>> Technical Advisor QGIS Project Steering Committee
>>
>>
>
>
> --
> -----------------
> Andrea Peri
> . . . . . . . . .
> qwerty àèìòù
> -----------------
>



-- 
-----------------
Andrea Peri
. . . . . . . . .
qwerty àèìòù
-----------------
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