Hi! On 2016/01/21 18:26, Kyotaro HORIGUCHI wrote: >>> Then, suppose we add a function bool ExecStartAsync(PlanState *target, >>> ExecCallback callback, PlanState *cb_planstate, void *cb_context). >>> For non-async-aware plan nodes, this just returns false. async-aware >>> plan nodes should initiate some work, register some callbacks, and >>> return. The callback that get registered should arrange in turn to >>> register the callback passed as an argument when a tuple becomes >>> available, passing the planstate and context provided by >>> ExecStartAsync's caller, plus the TupleTableSlot containing the tuple. >> >> Although I don't imagine clearly about the case of >> async-aware-nodes under non-aware-nodes, it seems to have a high >> affinity with (true) parallel execution framework. > > The ExecStartAsync is similar to ExecStartNode of my old > patch. One of the most annoying things of that is that it needs > to walk down to their descendents and in turn it needs garbageous > corresponding additional codes for all type of nodes which can > have children.
Unless I am missing something, I wonder if this is where planstate_tree_walker() introduced by commit 8dd401aa is useful. For example, I see that it's used in ExecShutdownNode() in a manner that looks interesting for this discussion. Thanks, Amit -- Sent via pgsql-hackers mailing list (email@example.com) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers