1. A computer-implemented method of managing a plurality of streams of data in a computer, the method comprising: processing the plurality of streams, to execute thereon a plurality of continuous queries based on an existing global plan; during said processing, receiving a new continuous query to be executed; during said processing, identifying from the existing global plan, a first operator that supplies data on a relation; during said processing, modifying the existing global plan by coupling the first operator to a second operator to be used to implement the new continuous query, thereby to obtain a modified global plan; prior to execution of the new continuous query, a processor in the computer selectively transmitting from the first operator to the second operator but not to a third operator in the existing global plan, a current value of the relation; prior to receipt of the new continuous query, said current value being transmitted to the third operator from the first operator by use of at least one reference and said at least one reference being deleted after said current value being read by the third operator during said processing based on the existing global plan; altering said processing, to cause execution of the new continuous query in addition to said plurality of continuous queries, based on the modified global plan; and outputting from said computer, a stream generated based at least partially on processing of said data by execution of the new continuous query.