Parallel Query

[Luís Roberto Weck <luisroberto@xxxxxxxxxxxxxxx>]

Hi!

Is there a reason query 3 can't use parallel workers? Using q1 and q2 
they seem very similar but can use up to 4 workers to run faster:

q1: https://pastebin.com/ufkbSmfB
q2: https://pastebin.com/Yt32zRNX
q3: https://pastebin.com/dqh7yKPb

The sort node on q3 takes almost 12 seconds, making the query run on 68  
if I had set enough work_mem to make it all in memory.

Running version 10.10.