I am currently trying to determine the 2 nearest points for a database of 8 million people against 425 locations.
I have 2 csv files uploaded into QGIS one with a unique number for 8 million people with a latitude and longitude. The second csv has 425 locations with a latitude and longitude. I then start the distance matrix analysis under the QGIS Geoalgorithms section of the processing tools feature.
Once I set it up and tell the analysis to run it begins. However, it takes about 4 hours to process which is not bad when considering the amount of calculations I am asking, but when I open the task manager QGIS is only using 20% of CPU and 150 MB of RAM.
To test it further I opened up to instances of QGIS running the same distance matrix and both are running at about 150 MB.
Is there a known limit of RAM use for vector analysis where it is reading from a CSV and writing to a new csv output?
I am currently using QGIS 2.14.15-Essen on Windows 8 with an i7 and 32 GB of RAM.