@Override
  protected void decideExecMode(List<Task<?>> rootTasks, Context ctx,
      GlobalLimitCtx globalLimitCtx)
      throws SemanticException {
    // currently all Tez work is on the cluster
    return;
  }
TezCompiler translates the operator plan into TezTasks.
ql/src/java/org/apache/hadoop/hive/ql/parse/TezCompiler.java