/** {@inheritDoc} */
public boolean putNoOverwrite(
DbTransaction txn, byte[] key, byte[] value)
{
try {
OperationStatus status = db.putNoOverwrite(
BdbTransaction.getBdbTxn(txn), new DatabaseEntry(key),
new DatabaseEntry(value));
if (status == SUCCESS) {
return true;
} else if (status == KEYEXIST) {