[Qgis-developer] Reverse Changeset 13499

[Chris Crook]

I guess the point is that, as you rightly note, the feature count isn't very important, so having it wrong really doesn't matter.  On the other hand having a responsive interface is important.  

Optimisations like only filling in the metadata when it is required are great - they add value whether you are using estimated metadata or not.  

Where you do need to use the full metadata and properly interrogate the database (such as your example with mixed geometries), then the you can just turn this option off.

Cheers
Chris


________________________________________
From: qgis-developer-bounces at lists.osgeo.org [qgis-developer-bounces at lists.osgeo.org] On Behalf Of Jürgen E. Fischer [jef at norbit.de]
Sent: 19 May 2010 19:02
To: qgis-developer at lists.osgeo.org
Subject: Re: [Qgis-developer] Reverse Changeset 13499

Hi,

On Wed, 19. May 2010 at 12:17:15 +1200, Chris Crook wrote:
> Yes .. It is wrong!  But the point of the estimated metadata isn't to get it
> right.  The point is that with very large tables, getting it right takes much
> too long - taking minutes to open layers (even if its only the first time
> with a lazy implementation) is very painful!

But only if you set a where clause.  In which case the feature count is likely
to be much different from the full feature count.

Or do you have tables with mixed geometry types, that are always accessed with
a where clause to get a unique geometry type?

I now also changed filling the metadata page in vector properties only if the
user wants to see it.

Another place where the feature count is used is to show progress in
symbology-ng, although that doesn't seem to make much sense, unless you are at
full layer extent.


Jürgen

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