Hi Andreas, Am Montag, 9. August 2010, um 14.29:12 schrieb Andreas Neumann: > Hi all, > > I wonder if the current Postgis-Provider somehow supports or would support > compression during data-transfer between the QGIS-client and the remote > Postgis-server. In my experience, data transfer across slower connection > (DSL, cable) is often rather slow. > > Would there be, technically, a way to accelerate data transfer over slower > network connections?
I don't know a built-in method for compressing data transfer on Postgres connections (http://www.postgresql.org/docs/current/static/libpq- connect.html). But you could tunnel the connection e.g. with netcat or ssh (without encryption) and compress it with gzip. Other solutions would be a compressed geometry format (like http://www.gaia-gis.it/spatialite-2.4.0/) or a partial update method. Both would need changes or custom stored procedures within Postgis. A different approach would be using an "offline" database and synchronizing with the master database. (We're currently working on this approach in a customer project). > > I also remember that Sandro Santilli once suggested a keyword substitution > parameter for the psql provider so one could use simplify based on map > resolution/map scale. This should also help to speed up data transfer on > slower connections > (http://lists.osgeo.org/pipermail/qgis-developer/2010-May/009923.html) - > unfortunately noone answered to his mail. I think the proposal would be > interesting to follow. You're asking for something like http://tinyurl.com/pgvar I think. QGIS could provide useful variables (like :scale) and offer a possibility to configure the select statements. Another way to achieve this could be using custom variables like in http://www.pgsql.cz/index.php/PostgreSQL_SQL_Tricks#Any_other_session_variables Regards Pirmin -- Pirmin Kalberer Sourcepole - Linux & Open Source Solutions http://www.sourcepole.com _______________________________________________ Qgis-developer mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/qgis-developer
