public static HiveVectorAdaptorUsageMode getHiveConfValue(HiveConf hiveConf) {
      String string = HiveConf.getVar(hiveConf,
          HiveConf.ConfVars.HIVE_VECTOR_ADAPTOR_USAGE_MODE);
      return valueOf(string.toUpperCase());
    }
Context class for vectorization execution.
Main role is to map column names to column indices and serves as a
factory class for building vectorized expressions out of descriptors.
ql/src/java/org/apache/hadoop/hive/ql/exec/vector/VectorizationContext.java