Calculating centroid for polygon layer with several features?

Question

I need only 1 centroid point for the whole layer (more than one polygon) instead of 1 centroid point per feature that you get with the menu -> Vector -> Geometry tools -> polygon centroid tool. Its position doesn't have to be based on area or weight of any kind.

Answer 1

With a virtual Layer you can do it like this (same as user30184 described in his comment):

select st_centroid(st_union(geometry)) from my_layer