Function transformWholeRowRef

src/backend/parser/parse_expr.c:2677–2736

* Construct a whole-row reference to represent the notation "relation.*". */

 * Construct a whole-row reference to represent the notation "relation.*".
 */
static Node *
transformWholeRowRef(ParseState *pstate, ParseNamespaceItem *nsitem,
					 int sublevels_up, int location)
{
	/*
	 * Build the appropriate referencing node.  Normally this can be a
	 * whole-row Var, but if the nsitem is a JOIN USING alias then it contains
	 * only a subset of the columns of the underlying join RTE, so that will
	 * not work.  Instead we immediately expand the reference into a RowExpr.
	 * Since the JOIN USING's common columns are fully determined at this
	 * point, there seems no harm in expanding it now rather than during
	 * planning.
	 *
	 * Note that if the RTE is a function returning scalar, we create just a
	 * plain reference to the function value, not a composite containing a
	 * single column.  This is pretty inconsistent at first sight, but it's
	 * what we've done historically.  One argument for it is that "rel" and
	 * "rel.*" mean the same thing for composite relations, so why not for
	 * scalar functions...
	 */
	if (nsitem->p_names == nsitem->p_rte->eref)
	{
		Var		   *result;

		result = makeWholeRowVar(nsitem->p_rte, nsitem->p_rtindex,
								 sublevels_up, true);

		/* location is not filled in by makeWholeRowVar */
		result->location = location;

		/* mark relation as requiring whole-row SELECT access */
		markVarForSelectPriv(pstate, result);

		return (Node *) result;
	}
	else
	{
		RowExpr    *rowexpr;
		List	   *fields;

		/*
		 * We want only as many columns as are listed in p_names->colnames,
		 * and we should use those names not whatever possibly-aliased names
		 * are in the RTE.  We needn't worry about marking the RTE for SELECT
		 * access, as the common columns are surely so marked already.
		 */
		expandRTE(nsitem->p_rte, nsitem->p_rtindex,
				  sublevels_up, location, false,
				  NULL, &fields);
		rowexpr = makeNode(RowExpr);
		rowexpr->args = list_truncate(fields,
									  list_length(nsitem->p_names->colnames));
		rowexpr->row_typeid = RECORDOID;
		rowexpr->row_format = COERCE_IMPLICIT_CAST;
		rowexpr->colnames = copyObject(nsitem->p_names->colnames);
		rowexpr->location = location;

		return (Node *) rowexpr;