if(isBDB && _joinPredicate == null){
throw new RuntimeException("Please provide _joinPredicate if you want to run BDB!");
}
if(isBDB && (hierarchyPosition == StormComponent.FINAL_COMPONENT)){
_joiner = new StormDstTupleStorageBDB(_firstParent, _secondParent, this, allCompNames,
_joinPredicate, hierarchyPosition, builder, killer, conf);
} else if (_joinPredicate != null) {
_joiner = new StormDstTupleStorageJoin(_firstParent, _secondParent, this,
allCompNames, _joinPredicate, hierarchyPosition, builder, killer, conf);
} else if (partitioningType == StormJoin.DST_ORDERING){