for(final OperatorIDTuple opID: operand.getSucceedingOperators()){
opID.getOperator().removePrecedingOperator(operand);
}
operand.getSucceedingOperators().clear();
operand.setSucceedingOperator(new OperatorIDTuple(tempJoin, 0));
tempJoin.addPrecedingOperator(operand);
for(final OperatorIDTuple opID: bottomJoin.getSucceedingOperators()){
opID.getOperator().removePrecedingOperator(bottomJoin);
}
bottomJoin.getSucceedingOperators().clear();
bottomJoin.setSucceedingOperator(new OperatorIDTuple(tempJoin, 1));