Function ExplainNode

src/backend/commands/explain.c:1538–3024

* ExplainNode - * Appends a description of a plan tree to es->str * * planstate points to the executor state node for the current plan node. * We need to work from a PlanState node, not just a Plan node, in order to * get at the instrumentation data (if any) as well as the list of subplans. * * ancestors is a list of parent Plan and SubPlan nodes, most-closely-nested * first. These are

 * function signature from upstream.)
 */
static void
ExplainNode(PlanState *planstate, List *ancestors,
			const char *relationship, const char *plan_name,
			ExplainState *es)
{
	Plan	   *plan = planstate->plan;
	PlanState  *parentplanstate;
	ExecSlice  *save_currentSlice = es->currentSlice;    /* save */
	const char *pname;			/* node type name for text output */
	const char *sname;			/* node type name for non-text output */
	const char *strategy = NULL;
	const char *partialmode = NULL;
	const char *operation = NULL;
	const char *custom_name = NULL;
	ExplainWorkersState *save_workers_state = es->workers_state;
	int			save_indent = es->indent;
	bool		haschildren;
	bool		skip_outer=false;
	char       *skip_outer_msg = NULL;
	int			motion_recv;
	int			motion_snd;
	ExecSlice  *parentSlice = NULL;

	/* Remember who called us. */
	parentplanstate = es->parentPlanState;
	es->parentPlanState = planstate;

	/*
	 * If this is a Motion node, we're descending into a new slice.
	 */
	if (IsA(plan, Motion))
	{
		Motion	   *pMotion = (Motion *) plan;
		SliceTable *sliceTable = planstate->state->es_sliceTable;

		if (sliceTable)
		{
			es->currentSlice = &sliceTable->slices[pMotion->motionID];
			parentSlice = es->currentSlice->parentIndex == -1 ? NULL :
						  &sliceTable->slices[es->currentSlice->parentIndex];
		}
	}

	/*
	 * Prepare per-worker output buffers, if needed.  We'll append the data in
	 * these to the main output string further down.
	 */
	if (planstate->worker_instrument && es->analyze && !es->hide_workers)
		es->workers_state = ExplainCreateWorkersState(planstate->worker_instrument->num_workers);
	else
		es->workers_state = NULL;

	/* Identify plan node type, and print generic details */
	switch (nodeTag(plan))
	{
		case T_Result:
			pname = sname = "Result";
			break;