SQLAlchemy is a ORM it's not going to help with any kind of caching. There are plans for creating a in memory feature cache of sorts so that we don't have to fetch each feature everytime however there is a bit of work involved in making sure we update the view when the data source changes.
- Nathan On Tue, Aug 6, 2013 at 7:33 PM, Angelos Tzotsos <[email protected]>wrote: > Hi all, > > I am *guessing* that Manifold is using the .NET Dataset type to cache > data, and that some kind of db manager takes care of the sync. > > SQLAlchemy could be used in a python plugin for the same purpose. > > Best, > Angelos > > > > On Tue, Aug 6, 2013 at 9:46 AM, Marco Hugentobler < > [email protected]> wrote: > >> Hi Willem >> >> Another thing to explore is the offline editing plugin. It caches postgis >> layers to a local spatialite database and can even be used to synchronise >> edits between local spatialite db and remote postgis db. >> >> >> >Sourcepole have developed (for NIWA, New Zealand) a plugin that supports >> local caching of WMS & WFS data sources. This could probably be adapted to >> support other input >formats. Marco Hugentobler did the coding for this - >> he can perhaps comment? >> >> The plugin saves WMS as local rasters and WFS as local vectors. This is >> similar to save as local vector / raster file by hand. However the plugin >> is more convenient because it manages the local storage and the reference >> to the remote uri. It has some other nice features like synchronizing / >> offlining in a graphical way. Btw., we hope to include this plugin (a C++ >> one) into the main repository after 2.0 feature freeze is over. >> >> Regards, >> Marco >> >> On 06.08.2013 03:20, Brent Wood wrote: >> >> Hi Willem, >> >> Why can you not save such a layer or a selection from such a layer, as >> a local shapefile (or other supported format). is this not effectively a >> "local cache"? Delete/overwrite when you desire. >> >> Where is the performance bottleneck? Postgis, network, QGIS? Just >> creating a local cache will not necessarily speed things up, if your >> database is on a fast server with a fast network, it may even get slower. >> >> Sourcepole have developed (for NIWA, New Zealand) a plugin that >> supports local caching of WMS & WFS data sources. This could probably be >> adapted to support other input formats. Marco Hugentobler did the coding >> for this - he can perhaps comment? >> >> As Nathan says, caching a local snapshot of a dynamic, multi-user >> database will result in something that gets out of sybc with the source >> pretty quickly. Caching a local copy of a largely static database is >> relatively safe. >> >> Cheers >> >> Brent >> ------------------------------ >> *From:* Nathan Woodrow <[email protected]> <[email protected]> >> *To:* Willem Buitendyk <[email protected]> <[email protected]> >> *Cc:* qgis-user <[email protected]> <[email protected]>; >> "[email protected]" <[email protected]> >> <[email protected]> <[email protected]> >> *Sent:* Tuesday, August 6, 2013 11:07 AM >> *Subject:* Re: [Qgis-user] Caching remote postgis layers? >> >> Hey Willem, >> >> I'm not aware of a feature like that. The best place to ask this >> question to see if anyone is working, or planning to work, on it is the >> developer list. I have copied it in so it show up there too. >> >> Caching could be done by storing the returned results in a memory >> spatialite database. The tricky thing is knowing when to get any new >> results from the postgis database when things have changed on the database. >> How does Manifold handling viewing an area, updating something using SQL >> on the database (not though Manifold) and then looking at that area again? >> >> - Nathan >> >> >> On Tue, Aug 6, 2013 at 2:44 AM, Willem Buitendyk <[email protected]>wrote: >> >> I've noticed looking at the roadmap that caching remote postgis data is >> not on the list. I love qgis but a lot of my work involves connecting to a >> remote postgis database. The speed of navigating a large dataset is, at >> the moment, rather unbearable. I also use Manifold GIS and the difference >> in speed is shocking, presumably because Manifold is caching the dataset. >> This seems like it should be a relatively easy thing to implement. Is >> there interest on this board for this feature? I was thinking at taking a >> stab at contributing to the source code but am wondering about methods to >> achieve data caching most efficiently. Look forward to others thoughts? >> Or maybe I missing something that is already in place? >> >> Willem >> >> _______________________________________________ >> Qgis-user mailing list >> [email protected] >> http://lists.osgeo.org/mailman/listinfo/qgis-user >> >> >> >> _______________________________________________ >> Qgis-user mailing list >> [email protected] >> http://lists.osgeo.org/mailman/listinfo/qgis-user >> >> >> >> >> _______________________________________________ >> Qgis-developer mailing >> [email protected]http://lists.osgeo.org/mailman/listinfo/qgis-developer >> >> >> >> -- >> Dr. Marco Hugentobler >> Sourcepole - Linux & Open Source Solutions >> Weberstrasse 5, CH-8004 Zürich, [email protected] >> http://www.sourcepole.ch >> Technical Advisor QGIS Project Steering Committee >> >> >> _______________________________________________ >> Qgis-developer mailing list >> [email protected] >> http://lists.osgeo.org/mailman/listinfo/qgis-developer >> >> > > > -- > Angelos Tzotsos > Remote Sensing Laboratory > National Technical University of Athens > http://users.ntua.gr/tzotsos > > _______________________________________________ > Qgis-developer mailing list > [email protected] > http://lists.osgeo.org/mailman/listinfo/qgis-developer > >
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