[Qgis-developer] how to avoid full-table scans to determine primary key, extents?

Chris Nicholas cnicholas at housecanary.com
Tue Nov 15 13:46:20 PST 2016

to be clear, PostGIS layers added using the option “select at id” , and then saved within a QGIS XML project file, will load from that project file very fast from then on?

Can I distribute project files with this option embedded in it, so that I might “suffer for the sake of others” and they have a pleasant experience seeing what I have authored?

thank you
Chris Nicholas

> On Nov 15, 2016, at 3:26 AM, Giovanni Manghi <giovanni.manghi at gmail.com> wrote:
> Hi,
>> Could you check if an issue mentioning this problem exists already
>> on hub.qgis.org and add one if not already present ?
>> I've had the same impression and it is possible this was a regression.
>> It'd be great to have an automated test guarding against full table
>> scans with PostGIS, to secure the feature once for all..
> this is my observation on 2.14.8:
> if the postgis layer is added (via the "add postgis layer" dialog)
> with the "select at id" checkbox then when opening the attribute table
> this is iterated one time. If the table is large browsing it is not
> very snappy.
> If the layer is added without the "select at id" thing, then the table
> is always iterated twice before opening. If the "show features visible
> on map" option is selected, the table is still iterated  twice (the
> entire table, not only the records of visible features) before
> opening. Browsing of large tables (once opened) is fast.
> One ticket I found that may be related
> http://hub.qgis.org/issues/10619
> cheers
> -- G --
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