Fix buffer usage stats for nodes above Gather Merge.

Amit Kapila · Amit Kapila · commit bdaa84e38932 · 2020-07-25T10:38:46.000+05:30
Commit 85c9d34 addressed a similar problem for Gather and Gather Merge nodes but forgot to account for nodes above parallel nodes. This still works for nodes above Gather node because we shut down the workers for Gather node as soon as there are no more tuples. We can do a similar thing for Gather Merge as well but it seems better to account for stats during nodes shutdown after completing the execution. Reported-by: Stéphane Lorek, Jehan-Guillaume de Rorthais Author: Jehan-Guillaume de Rorthais <jgdr@dalibo.com> Reviewed-by: Amit Kapila Backpatch-through: 10, where it was introduced Discussion: https://postgr.es/m/20200718160206.584532a2@firost
diff --git a/src/backend/executor/execProcnode.c b/src/backend/executor/execProcnode.c
@@ -746,8 +746,6 @@ ExecShutdownNode(PlanState *node)
 
 	check_stack_depth();
 
-	planstate_tree_walker(node, ExecShutdownNode, NULL);
-
 	/*
 	 * Treat the node as running while we shut it down, but only if it's run
 	 * at least once already.  We don't expect much CPU consumption during
@@ -761,6 +759,8 @@ ExecShutdownNode(PlanState *node)
 	if (node->instrument && node->instrument->running)
 		InstrStartNode(node->instrument);
 
+	planstate_tree_walker(node, ExecShutdownNode, NULL);
+
 	switch (nodeTag(node))
 	{
 		case T_GatherState:
