I am joining two tables, each with 32K tuples. The query runs for ~23-24 seconds on my (multi-core) machine.

During execution, however, only 1 core is utilised, while the rest of the CPU cores are idle. The cores are under-utilised although I have configured the MonetDB server to use all the physical cores of my machine (either by setting 'nthreads' or, in the case of mserver5, 'gdk_nr_threads').

I am running MonetDB server v11.21.13 "Jul2015-SP2", compiled from source.

Is this due to some configuration setting I missed? Or, due to the fact that I am running a single-operator query?

Alternatively, I was thinking of creating merge tables, thus partitioning my tables manually, hoping that this will allow for intra-operator parallelism.

Thanks,

Alexandros