Function expandRTE

src/backend/parser/parse_relation.c:2910–3258

* expandRTE -- expand the columns of a rangetable entry * * This creates lists of an RTE's column names (aliases if provided, else * real names) and Vars for each column. Only user columns are considered. * If include_dropped is false then dropped columns are omitted from the * results. If include_dropped is true then empty strings and NULL constants * (not Vars!) are returned for dropped

 * output pointer for the unwanted one.
 */
void
expandRTE(RangeTblEntry *rte, int rtindex, int sublevels_up,
		  int location, bool include_dropped,
		  List **colnames, List **colvars)
{
	int			varattno;

	if (colnames)
		*colnames = NIL;
	if (colvars)
		*colvars = NIL;

	switch (rte->rtekind)
	{
		case RTE_RELATION:
			/* Ordinary relation RTE */
			expandRelation(rte->relid, rte->eref,
						   rtindex, sublevels_up, location,
						   include_dropped, colnames, colvars);
			break;
		case RTE_SUBQUERY:
			{
				/* Subquery RTE */
				ListCell   *aliasp_item = list_head(rte->eref->colnames);
				ListCell   *tlistitem;

				varattno = 0;
				foreach(tlistitem, rte->subquery->targetList)
				{
					TargetEntry *te = (TargetEntry *) lfirst(tlistitem);

					if (te->resjunk)
						continue;
					varattno++;
					Assert(varattno == te->resno);

					/*
					 * In scenarios where columns have been added to a view
					 * since the outer query was originally parsed, there can
					 * be more items in the subquery tlist than the outer
					 * query expects.  We should ignore such extra column(s)
					 * --- compare the behavior for composite-returning
					 * functions, in the RTE_FUNCTION case below.
					 */
					if (!aliasp_item)
						break;

					if (colnames)
					{
						char	   *label = strVal(lfirst(aliasp_item));

						*colnames = lappend(*colnames, makeString(pstrdup(label)));
					}

					if (colvars)
					{
						Var		   *varnode;