Hi hackers, I'm working on a CSP and started wondering about the semantics of ExecShutdownNode(). The documentation suggests that it can be used for freeing resources early. Early meaning as soon as it's known that no more rows need to be produced. For that, ExecutePlan() calls ExecShutdownNode(), once all tuples got produced and no backscan is possible.
However, reading through the code it seems to me that the function got introduced for the purpose of being able to cleanup resources before the DSM segment is removed. I cannot see how it could safely be used for other purposes: ExecutePlan() calls ExecShutdownNode() even though ExecutePlan() is possibly called again, e.g. when a cursor is used. It looks like the existing code only works because parallelism is disabled for all cases where ExecutePlan() might be invoked multiple times (e.g. user cursors). Can someone please shed some light on the intended use case? I'm planning to conserve any learnings from this thread in src/executor/README. -- David Geier
