[Qgis-user] Adding layer slows down QGIS dramatically after adding a layer

[Richard Duivenvoorde]

On 8/13/20 3:57 PM, Peter Cornelissen wrote:
> Hi
> 
> I am using a Geopackage with about 15 tables (a mixture of lines, polygons and points), but each of these tables are
> used 40 or 50 times with filters as many of the elements are used on multiple layers.
> However, I am now finding that as soon as I add a new layer QGIS slows down
> and it is taking 60 seconds or more to do almost any action that involves
> redrawing (zoom in/out/ pan etc) or even moving a layer within the layers
> panel. If I save the project, close down QGIS and restart, it is fine again
> until the next time.
> 
> Any suggestions?
> 
> Thanks, Peter

Looking at the attributes which are used in the filters, add 'indexes' too the tables in the Geopackage? 

In QGIS you can do that by creating a connection to the gpkg with DataBase Manager and then:
 'edit table' > tab indexes, > add index

A geopackage is a sqlite database, so if you have some sql-client (DB-manager, DB-browser) you can fire the create index query there:
CREATE INDEX "foo_index" ON "mygeopackage" ("foo_column")

Note that these are plain indexes, no spatial ones.
IF your filters are spatial filters, then off course you need spatial indexes.

HTH

Regards,

Richard Duivenvoorde