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]>
To: Willem Buitendyk <[email protected]>
Cc: qgis-user <[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
>
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