public static boolean getIsVectorized(Configuration conf) {
    if (conf.get(VECTOR_MODE) != null) {
      // this code path is necessary, because with HS2 and client
      // side split generation we end up not finding the map work.
      // This is because of thread local madness (tez split
      // generation is multi-threaded - HS2 plan cache uses thread
      // locals).
      return
          conf.getBoolean(VECTOR_MODE, false);
    } else {
      if (HiveConf.getBoolVar(conf, HiveConf.ConfVars.HIVE_VECTORIZATION_ENABLED) &&
        Utilities.getPlanPath(conf) != null) {
        MapWork mapWork = Utilities.getMapWork(conf);
        return mapWork.getVectorMode();
      } else {
        return false;
      }
    }
  }
Returns true if a plan is both configured for vectorized execution
and the node is vectorized.

The plan may be configured for vectorization
but vectorization disallowed eg. for FetchOperator execution.
ql/src/java/org/apache/hadoop/hive/ql/exec/Utilities.java