[Qgis-developer] guestimating plug-in dev time?

Mon Jan 19 04:19:32 PST 2015

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
>
>                 _______________________________________________
>                 Qgis-developer mailing list
>                 Qgis-developer at lists.osgeo.org
>                 <mailto:Qgis-developer at lists.osgeo.org>
>                 http://lists.osgeo.org/mailman/listinfo/qgis-developer
>
>
>
>
>
>
>
> _______________________________________________
> Qgis-developer mailing list
> Qgis-developer at lists.osgeo.org
> http://lists.osgeo.org/mailman/listinfo/qgis-developer

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.osgeo.org/pipermail/qgis-developer/attachments/20150119/eba7dcc2/attachment.html>