def _can_lower_sort_column(table_set, expr):
    # TODO(wesm): This code is pending removal through cleaner internal
    # semantics

    # we can currently sort by just-appeared aggregate metrics, but the way
    # these are references in the expression DSL is as a SortBy (blocking
    # table operation) on an aggregation. There's a hack in _collect_SortBy
    # in the generic SQL compiler that "fuses" the sort with the
    # aggregation so they appear in same query. It's generally for
    # cosmetics and doesn't really affect query semantics.
    bases = ops.find_all_base_tables(expr)
    if len(bases) > 1:
        return False

    base = list(bases.values())[0]
    base_op = base.op()

    if isinstance(base_op, ops.Aggregation):
        return base_op.table.equals(table_set)
    elif isinstance(base_op, ops.Selection):
        return base.equals(table_set)
    else:
        return False
dataset/ETHPy150Open cloudera/ibis/ibis/sql/alchemy.py/_can_lower_sort_column/original