I have a PostGIS dataset with around 3 million shapes. I only need to view about 1,500 of these shapes at any given time, but the shapes I need to see depends on which feature is selected in a different dataset.
My question is: what is the speed difference between filtering my large dataset within PostGIS and then serving it up to QGIS, vs loading the entire dataset into QGIS and then using the baked-in layer filtering? I'm running PostGIS 2 and QGIS 1.8.
I assume PostGIS is faster, but how much faster? I'd like a second opinion before I spend my time coding for one solution over the other. Thanks!