I made sure EXPLAIN returns CustomScan for all scans in the query. But still, ExecCustomScan is only called once while the rest of the functions are called for each scan separately. Is this expected behavior? How to work around this?
Amin <amin.fallahi@gmail.com> writes: > To simplify: Can CustomScan scan multiple relations in the same query or it > will always be assigned to one or zero relations?
There's barely any code in the core planner that is specific to custom scans. Almost certainly this misbehavior is the fault of your custom-path-creation code. Maybe you're labeling the paths with the wrong parent relation, or forgetting to submit them to add_path, or assigning them costs that are high enough to get them rejected?