[Qgis-developer] guestimating plug-in dev time?
George Silva
georger.silva at gmail.com
Mon Jan 19 04:31:20 PST 2015
I also have a lot of experience with a large number of users (around 15)
editing a central database with PostGIS. No problems there.
Remi, the development time for this would be around a day. If you wish to
outsource that job, I have some experience with QGIS Plugins and I could
develop that for you.
George
On Mon, Jan 19, 2015 at 10:29 AM, Bernhard Ströbl <bernhard.stroebl at jena.de>
wrote:
> Hi Andreas,
>
> I do not think that multi-core rendering is the issue here as Remi
> mentions to have experienced crashes since QGIS 1.8.
>
> Remi,
> I am using QGIS with Postgres/PostGIS with some dozens of users on a
> central database _without_ any issues in QGIS (except the multi-core issue
> Andreas mentioned). So do share your problems together with relevent parts
> of your data base so they can beanalyzed.
>
> Bernhard
>
> Am 19.01.2015 13:19, schrieb Andreas Neumann:
>
>> Hi Remi,
>>
>> Regarding crashes with Postgis: do you have multithreading with a lot of
>> CPU cores active? I am experiencing crashes if more than 2 cores are
>> active. Try limiting to 2 CPU cores and see if this helps.
>>
>> Still trying to investigate this issue with the devs.
>>
>> Besides the above issue, editing with Postgis works stable for me -
>> certainly not as many crashes as you say you have.
>>
>> Please do not ignore the crashes but try to report them so that the devs
>> can do something about it.
>>
>> Andreas
>>
>> On 19.01.2015 11:57, Rémi Cura wrote:
>>
>>> I think a more global solution is possible.
>>> After all when you load a postgis layer in qgis, if somebody else
>>> changes it, the view is not refreshed, which is annoying (and
>>> sometimes dangerous because you may edit old data).
>>>
>>> It would be easy to ad this (which would also work for my case) using
>>> the LISTEN / NOTIFY feature of postgres.
>>>
>>> Basically when selecting a table as a new qgis layer, you
>>> automatically add a triger to it.
>>> The trigger will be fired at any change (create/delete/update).
>>> The trigger would simply send a message to qgis via NOTIFY.
>>> example : "NOTIFY qgis_change_XXXX ;", where XXXX is a unique id.
>>> Of course qgis would be listening, which is very simple in python
>>> (import psycopg2;
>>> conn = psycopg.connect(my_database_string)
>>> conn.autocommit(1)
>>> curs = conn.cursor()
>>> curs.execute("LISTEN qgis_change_XXXX;"))
>>>
>>> Of course one would need a mechanism to remove this trigger when not
>>> necessary (for instance, name the channel "qgis_change_/time_stamp/",
>>> delete channel too old automatically, and change channel periodically
>>> (20 in for instance)).
>>>
>>> I don't know if from a security point of view it would be possibe
>>> tough (would require the permission to create a trigger).
>>> I don't know if typical qgis user have the right to create trigger on
>>> database they use.
>>>
>>> I use a lot of different version of QGIS and I can guarantee at least
>>> a dozen crash a day with version 1.8 to 2.3,
>>> plus pending transaction with postgis whenever the crash occurs.
>>> I'm installing 2.6 to see if postgis layers are less fragile right now ^^
>>>
>>> Cheers,
>>> Rémi-C
>>>
>>> 2015-01-19 11:29 GMT+01:00 Martin Dobias <wonder.sk at gmail.com
>>> <mailto:wonder.sk at gmail.com>>:
>>>
>>> I see - indeed QGIS would need to do quite some database
>>> inspection to understand that layer A and layer B are related.
>>> This should be however also easy to address in a custom plugin.
>>>
>>> It is surprising to me that you say PostGIS layers are fragile in
>>> QGIS - they are very commonly used by lots of people and we
>>> haven't heard about crashes in the issue tracker. If you do
>>> experience crashes please consider filing reports on hub.qgis.org
>>> <http://hub.qgis.org> with instructions on how to replicate them.
>>>
>>> Regards
>>> Martin
>>>
>>>
>>> On Mon, Jan 19, 2015 at 5:18 PM, Rémi Cura <remi.cura at gmail.com
>>> <mailto:remi.cura at gmail.com>> wrote:
>>>
>>> Thanks Martin,
>>> one day to several days feel like a very reasonnable order of
>>> magnitude.
>>>
>>> QGis is not refreshing the view because when editing layer A
>>> the postgis data base automatically also edit layer B.
>>> I don't think qgis has a mechanism of tracking dbchanges (it
>>> would be possible tough).
>>> Morevover PostGIS layer are still "fragile" in qgis (crashes
>>> often).
>>>
>>> Thanks for the help,
>>> Cheers
>>> Rémi-C
>>>
>>> 2015-01-19 10:56 GMT+01:00 Martin Dobias <wonder.sk at gmail.com
>>> <mailto:wonder.sk at gmail.com>>:
>>>
>>> Hi Remi
>>>
>>> Such plugin should be quite easy to write - I would assume
>>> up to one day of work for an experienced pyqgis developer.
>>> For a newcomer it may take few more days to get familiar
>>> with the API, tools, environment and so on.
>>>
>>> For the refresh of rendering after geometry editing - that
>>> should work out of the box and I would consider it a bug
>>> if it does not.
>>>
>>> Regards
>>> Martin
>>>
>>>
>>> On Mon, Jan 19, 2015 at 3:16 PM, Rémi Cura
>>> <remi.cura at gmail.com <mailto:remi.cura at gmail.com>> wrote:
>>>
>>> Hello dear list.
>>> I'm usually active on the postgis or postgres list,
>>> but today I would like to ask a question regarding dev
>>> time.
>>>
>>> In your opinion,
>>> How much time would be needed to write a plugin for
>>> multiple versions of qgis (2.2 to current 2.6) doing 3
>>> simple things :
>>> - auto commit the edition of geometry when in edition
>>> mode (no need to click on save changes each time)
>>> - force refresh of rendering after edition of a geometry
>>> - every camera changes (zoom or position), send a sql
>>> query containing user name and geometry of view (a
>>> rectangle in wkt for instance).
>>>
>>> I can estimate this at my poor qgis-dev level, but I
>>> would like to have the timing for an expert qgis dev.
>>>
>>> Many thanks,
>>>
>>> Remi-C
>>>
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>>>
>>>
>>>
>>>
>>>
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--
George R. C. Silva
SIGMA Consultoria
----------------------------
http://www.consultoriasigma.com.br/
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