public void addProjectionColumn(String columnName, int vectorBatchColIndex) {
    if (vectorBatchColIndex < 0) {
      throw new RuntimeException("Negative projected column number");
    }
    projectedColumns.add(vectorBatchColIndex);
    projectionColumnNames.add(columnName);
    projectionColumnMap.put(columnName, vectorBatchColIndex);
  }
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