[Qgis-user] QGIS and Oracle native connection

[Jürgen E. Fischer]

Hi Jonathan,

On Mon, 13. May 2013 at 13:06:49 +0100, Jonathan Moules wrote:
> 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!).

Can you work out which queries take particularly long (I added some progress
messages recently)?

> Does QGIS need to do all of the checks it does when actually listing the
> tables?

Well, QGIS needs to know which geometry types are present.  And that might take
long to determine.   It might be possible to do that lazy - ie. on demand
(introduce another level to the tree where the types in the geometry column
are.

> 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.

You can "stop" the detection and then pick what's already there.

> Panning. Again, fine with smaller datasets, but the larger ones cause
> issues.

Do you have numeric primary keys?  Otherwise QGIS must build a map that assigns
numeric keys to the primary keys (or ROWID if there isn't any primary key) on
the client side.


Jürgen

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