/*
* remove old connections of the 2nd subgraph (because it
* should be included into the subgraph)
*/
for (OperatorIDTuple op : bisSucc) {
bis.removeSucceedingOperator(op);
op.getOperator().removePrecedingOperator(bis);
}
/*
* connect the basic index scan and the 2nd subgraph
* container in the join-operator in the 1st subgraph