@Override
  public LockResponse acquireMaterializationRebuildLock(String dbName, String tableName, long txnId)
      throws LockException {
    // This is default implementation. Locking only works for incremental maintenance
    // which only works for DB transactional manager, thus we cannot acquire a lock.
    return new LockResponse(0L, LockState.NOT_ACQUIRED);
  }
Gets the lock manager and verifies if the explicit lock is supported
@return  the lock manager
@throws HiveException
ql/src/java/org/apache/hadoop/hive/ql/lockmgr/HiveTxnManagerImpl.java