[Qgis-user] QGIS and Oracle native connection

[Jonathan Moules]

Hi Jürgen,
Thanks again for this. I've now had the chance to do a little playing with
it. And have some feedback below (along with the already-filed tickets).

My primary observation is that its slow I'm afraid.

-----

The first and most obvious thing is that it's incredibly slow to list the
tables. I don't know how many tables were used in the test setup, but we
have over a thousand spatial tables ranging from one row to 20 million on
an Oracle Locator 10g setup that has about 50 concurrent users.

In the best case scenario ("Only look in meta data table" and "Use
estimated table metadata" both checked), it still takes a full *two
minutes*to list all of the tables. If I don't have those checkboxes
checked it
takes much longer (scanning the table that has ~20million features alone
takes about a minute!).

Does QGIS need to do all of the checks it does when actually listing the
tables? Could it not do them when they are selected for adding instead? We
have half a dozen other GIS program's that connect to Oracle and none of
them are even close to being this slow to produce the table list.

Its also impossible to "add" a table while the list is being generated so
the user has to wait until its finished before being able to continue.
Though it does seem to get a little faster on subsequent requests, even
restarting QGIS, but that's probably Oracle caching.

Note: I'm aware ArcGIS uses its ArcSDE tables and MapInfo uses its own
metadata table so its not an /entirely/ fair comparison.

-----

If I click "add" for a polygon dataset with ~7 million features (fully
indexed), it takes a full 90 seconds before it is even added to QGIS
(during this time QGIS is unresponsive)! This is with rendering turned off.
The 20 million polyline dataset takes 140 seconds to add, again, with
rendering off!

This is less noticeable with smaller datasets.

-----
Panning. Again, fine with smaller datasets, but the larger ones cause
issues.
The larger dataset (20 million features) is MasterMap Topographic Line, the
large scale mapping for the UK. If I view it at 1:5,000 (the furthest out
we use it), there are in a detailed urban scene about 40,000 features
on-screen.

In order of speed:

QGIS: ~4-16 seconds (no styling))
GeoServer WMS "single tile" : ~15 seconds (via
Openlayers, categorised styling)
MapInfo: ~9 seconds (includes categorised styling)
ArcGIS: ~4 seconds (includes categorised styling)
GeoServer WMS 256^2 tiled (no GWC cache): ~3 seconds (via
Openlayers, categorised styled)

The panning did get faster, I guess because Oracle started picking up on my
pans.

---
The short version is - is there anything I can do to speed this up? Are
these the expected speeds for these sorts of datasets/numbers?

I'm happy to do further testing if desired.

Jonathan



On 9 May 2013 16:13, Jürgen E. <jef at norbit.de> wrote:

> Hi Jonathan,
>
> On Wed, 08. May 2013 at 11:24:08 +0100, Jonathan Moules wrote:
> >    Anyone? I'd love to try this and test it, but can't if I have no idea
> how
> >    to even connect. Is there any documentation for it anywhere?
>
>
> https://github.com/qgis/Quantum-GIS/blob/master/resources/context_help/QgsOracleNewConnection-en_US
>
> Jürgen
>
> --
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