On Tue, 14 May 2024 at 02:07, Dimitrios Apostolou <jimis@xxxxxxx> wrote: > > On Tue, 14 May 2024, David Rowley wrote: > > Parallel Append can also run in a way that the Append child nodes will > > only get 1 worker each. > > How can I tell which case it is, from the EXPLAIN output (for example > the output at [1]) ? IIRC, the planner does prefer to use Parallel aware child Paths when creating a Parallel Append. Given equivalent costs, there's no advantage to it choosing a non-parallel aware Path. The planner does not have any optimisations that that would enable. However, it is possible that the planner *could* generate these. All the Append subpaths would just have to all be parallel safe but not parallel aware. You could identify them in EXPLAIN by seeing a "Parallel Append" without the "Parallel" in front of the node names in any of the Parallel Append's subpaths. David
