[Qgis-developer] Postgis Caching - Enhancement

[Bernhard Ströbl]

Hi Alex,

we are using a PostGIS database here with several clients connected at 
any point in time (geoserver and QGIS users). I am always impressed how 
fast QGIS draws even layers with many features and complex rules. Even 
when working on my old laptop with a local postgreSQL instance (base 
configuration) it is impressively fast. So I would not say that the 
PostGIS provider _in general_ is slow (as [1] suggests). Looking at 
OpenJump: are there configurations where caching really improves speed? 
If I understood the explanations right only those features intersecting 
the viewport are cached, so any panning/zooming results in a database 
request, too.
Still speed improvements are always welcome, but if a layer is read-only 
for one user this does not neccessarily mean that it is read-only for 
others, too, so care must be taken when to activate caching. Although 
there are definitely layers for which changes cannot be expected during 
one QGIS session, so caching (in memory) might improve performance. 
Looking at other providers I know that shape files from network drives 
are sloooowww. So I would opt for a generic approach that works with any 
provider.

my 2 cts

Bernhard

[1] http://gis.stackexchange.com/q/46967/3183

Am 01.04.2014 06:51, schrieb Alex Mandel:
> Searching tickets I don't see this one, but wanted to check that it
> wasn't on the roadmap.
>
> Often when working with Postgis layers, it's a read-only relationship
> directly to a table or view that is not expected to change anytime soon.
> To speed up panning/zooming etc we should implement and optional caching
> mechanism (maybe this is a general feature for all vector providers?).
>
> It's one of the only things I've seen OpenJump do that QGIS doesn't do
> at all. See the Check box in the add table dialog - Cache Features
> http://sourceforge.net/apps/mediawiki/jump-pilot/index.php?title=Working_with_Databases
>
> Topic comes up often:
> http://gis.stackexchange.com/q/46967/3183
> There are plenty of previous conversations like this around.
>
> If it's not anywhere in the plans I'll be happy to open a ticket.
>
> Thanks,
> Alex
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-- 
Bernhard Ströbl
Anwendungsbetreuer GIS

Kommunale Immobilien Jena
Am Anger 26
07743 Jena

Tel.: 03641 49- 5190
E-Mail: bernhard.stroebl at jena.de
Internet: www.kij.de


Kommunale Immobilien Jena
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