presto-main/src/main/java/io/prestosql/sql/planner/LocalDynamicFilter.java/LocalDynamicFilter/isFilterAboveTableScan
class LocalDynamicFilter:    private static boolean isFilterAboveTableScan(PlanNode node)
    {
        if (node instanceof FilterNode) {
            if (((FilterNode) node).getSource() instanceof TableScanNode) {
                return true;
            }
        }
        return false;
    }