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

Giovanni Manghi giovanni.manghi at gmail.com
Tue Nov 15 03:26:15 PST 2016


> 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



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