Function ExpandColumnRefStar

src/backend/parser/parse_target.c:1117–1279

* ExpandColumnRefStar() * Transforms foo.* into a list of expressions or targetlist entries. * * This handles the case where '*' appears as the last or only item in a * ColumnRef. The code is shared between the case of foo.* at the top level * in a SELECT target list (where we want TargetEntry nodes in the result) * and foo.* in a ROW() or VALUES() construct (where we want just bare * exp

 * The referenced columns are marked as requiring SELECT access.
 */
static List *
ExpandColumnRefStar(ParseState *pstate, ColumnRef *cref,
					bool make_target_entry)
{
	List	   *fields = cref->fields;
	int			numnames = list_length(fields);

	if (numnames == 1)
	{
		/*
		 * Target item is a bare '*', expand all tables
		 *
		 * (e.g., SELECT * FROM emp, dept)
		 *
		 * Since the grammar only accepts bare '*' at top level of SELECT, we
		 * need not handle the make_target_entry==false case here.
		 */
		if (!make_target_entry)
			elog(ERROR, "invalid use of *");

		return ExpandAllTables(pstate, cref->location);
	}
	else
	{
		/*
		 * Target item is relation.*, expand that table
		 *
		 * (e.g., SELECT emp.*, dname FROM emp, dept)
		 *
		 * Note: this code is a lot like transformColumnRef; it's tempting to
		 * call that instead and then replace the resulting whole-row Var with
		 * a list of Vars.  However, that would leave us with the RTE's
		 * selectedCols bitmap showing the whole row as needing select
		 * permission, as well as the individual columns.  That would be
		 * incorrect (since columns added later shouldn't need select
		 * permissions).  We could try to remove the whole-row permission bit
		 * after the fact, but duplicating code is less messy.
		 */
		char	   *nspname = NULL;
		char	   *relname = NULL;
		ParseNamespaceItem *nsitem = NULL;
		int			levels_up;
		enum
		{
			CRSERR_NO_RTE,
			CRSERR_WRONG_DB,
			CRSERR_TOO_MANY
		}			crserr = CRSERR_NO_RTE;

		/*
		 * Give the PreParseColumnRefHook, if any, first shot.  If it returns
		 * non-null then we should use that expression.
		 */
		if (pstate->p_pre_columnref_hook != NULL)
		{
			Node	   *node;

			node = pstate->p_pre_columnref_hook(pstate, cref);