presto-main/src/main/java/io/prestosql/operator/index/FieldSetFilteringRecordSet.java/FieldSetFilteringRecordCursor/advanceNextPosition
class FieldSetFilteringRecordCursor:        @Override
        public boolean advanceNextPosition()
        {
            while (delegate.advanceNextPosition()) {
                if (fieldSetsEqual(delegate, fieldSets)) {
                    return true;
                }
            }
            return false;
        }