Function ExplainTargetRel

src/backend/commands/explain.c:4768–4926

* Show the target relation of a scan or modify node */

 * Show the target relation of a scan or modify node
 */
static void
ExplainTargetRel(Plan *plan, Index rti, ExplainState *es)
{
	char	   *objectname = NULL;
	char	   *namespace = NULL;
	const char *objecttag = NULL;
	RangeTblEntry *rte;
	char	   *refname;
	int			dynamicScanId = 0;

	rte = rt_fetch(rti, es->rtable);
	refname = (char *) list_nth(es->rtable_names, rti - 1);
	if (refname == NULL)
		refname = rte->eref->aliasname;

	switch (nodeTag(plan))
	{
		case T_SeqScan:
		case T_DynamicSeqScan:
		case T_SampleScan:
		case T_IndexScan:
		case T_DynamicIndexScan:
		case T_DynamicIndexOnlyScan:
		case T_IndexOnlyScan:
		case T_BitmapHeapScan:
		case T_DynamicBitmapHeapScan:
		case T_TidScan:
		case T_TidRangeScan:
		case T_ForeignScan:
		case T_DynamicForeignScan:
		case T_CustomScan:
		case T_ModifyTable:
			/* Assert it's on a real relation */
			Assert(rte->rtekind == RTE_RELATION);
			objectname = get_rel_name(rte->relid);
			if (es->verbose)
				namespace = get_namespace_name(get_rel_namespace(rte->relid));
			objecttag = "Relation Name";
			break;
		case T_FunctionScan:
			{
				FunctionScan *fscan = (FunctionScan *) plan;

				/* Assert it's on a RangeFunction */
				Assert(rte->rtekind == RTE_FUNCTION);

				/*
				 * If the expression is still a function call of a single
				 * function, we can get the real name of the function.
				 * Otherwise, punt.  (Even if it was a single function call
				 * originally, the optimizer could have simplified it away.)
				 */
				if (list_length(fscan->functions) == 1)
				{
					RangeTblFunction *rtfunc = (RangeTblFunction *) linitial(fscan->functions);

					if (IsA(rtfunc->funcexpr, FuncExpr))
					{