In section 15.3.4, I believe "multiple results sets" is a typo for "multiple result sets". It says:
> Plans that involve appending multiple results sets can therefore achieve coarse-grained parallelism even when efficient partial plans are not available.
It's also possible this should say "multiple results" rather than "multiple result sets".
Good catch, and an acceptable solution.
However, I'm inclined to write: "multiple inputs" at that spot:
Plans that involve appending multiple inputs can therefore achieve...
Using the term "result set" here just feels off, though that is a mostly uninformed (as to precedent) opinion.
I think result sets the correct term since the Append node is combining partial
results made by other parallel nodes. Doing some reading it seems to me that
"results sets" isn't incorrect (though I might have misunderstood the grammar
from not being a native speaker), but I'm still inclined to change since we
consistently use "result sets" in the rest of the documentation.
