public void init(TypeInfo[] typeInfos) throws HiveException {

    final int count = typeInfos.length;
    allocateArrays(count);

    for (int i = 0; i < count; i++) {
      initEntry(i, i, typeInfos[i]);
    }
  }
This class extracts specified VectorizedRowBatch row columns into writables.

The caller provides the data types and projection column numbers of a subset of the columns
to extract.
ql/src/java/org/apache/hadoop/hive/ql/exec/vector/VectorExtractRow.java