Function make_row_distinct_op

src/backend/parser/parse_expr.c:3070–3109

* Transform a "row IS DISTINCT FROM row" construct * * The input RowExprs are already transformed */

 * The input RowExprs are already transformed
 */
static Node *
make_row_distinct_op(ParseState *pstate, List *opname,
					 RowExpr *lrow, RowExpr *rrow,
					 int location)
{
	Node	   *result = NULL;
	List	   *largs = lrow->args;
	List	   *rargs = rrow->args;
	ListCell   *l,
			   *r;

	if (list_length(largs) != list_length(rargs))
		ereport(ERROR,
				(errcode(ERRCODE_SYNTAX_ERROR),
				 errmsg("unequal number of entries in row expressions"),
				 parser_errposition(pstate, location)));

	forboth(l, largs, r, rargs)
	{
		Node	   *larg = (Node *) lfirst(l);
		Node	   *rarg = (Node *) lfirst(r);
		Node	   *cmp;

		cmp = (Node *) make_distinct_op(pstate, opname, larg, rarg, location);
		if (result == NULL)
			result = cmp;
		else
			result = (Node *) makeBoolExpr(OR_EXPR,
										   list_make2(result, cmp),
										   location);
	}

	if (result == NULL)
	{
		/* zero-length rows?  Generate constant FALSE */
		result = makeBoolConst(false, false);
	}

	return result;
}

/*
 * make the node for an IS DISTINCT FROM operator