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

Chris Nicholas cnicholas at housecanary.com
Tue Nov 15 16:12:50 PST 2016

re-reading your post, I note the words:

"Browsing of large tables (once opened) is fast.”

yes; it is precisely that “once opened part” I am talking about, particularly when one has many views joined to a common large large geometry table..

Chris Nicholas

> On Nov 15, 2016, at 1:46 PM, Chris Nicholas <cnicholas at housecanary.com> wrote:
> 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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