/** Create from a different SCN with modifying a single partition sequence */
 public MultiPartitionSCN(MultiPartitionSCN other, int partitionIdx, long seq) {
   _seq = other.getSequences(partitionIdx < other._seq.length ? null : new long[partitionIdx + 1]);
   _seq[partitionIdx] = seq;
 }
 /** Copy constructor */
 public MultiPartitionSCN(MultiPartitionSCN other) {
   _seq = other.getSequences();
 }