Currently, I don't see many docs explaining what a PLAN_ROOT_SINK is, even though it shows up in explain plans and runtime profiles. After more of the changes in
IMPALA-8656 are merged, understanding what PLAN_ROOT_SINK is will be more important, because it will start taking up a memory reservation and possibly spilling to disk.
I don't see any docs on data sinks in general, so perhaps it would be useful to create a dedicated page for explaining data sinks and how they work. We can start by documenting the PLAN_ROOT_SINK as that may be the most commonly used one.
We should document all the changes being made in
IMPALA-8656 as well.