protected void initialize(Configuration hconf, ObjectInspector inputOI,
      int parentId) throws HiveException {
    LOG.debug("Initializing Child : {}", this);
    if (parentId >= inputObjInspectors.length) {
      // Determine the next power of 2 larger than the requested index
      int newLength = 2;
      while (parentId >= newLength) {
        newLength <<= 1;
      }
      inputObjInspectors = Arrays.copyOf(inputObjInspectors, newLength);
    }
    inputObjInspectors[parentId] = inputOI;
    // call the actual operator initialization function
    initialize(hconf, null);
  }
Collects all the parent's output object inspectors and calls actual
initialization method.

@param hconf
@param inputOI
         OI of the row that this parent will pass to this op
@param parentId
         parent operator id
@throws HiveException
ql/src/java/org/apache/hadoop/hive/ql/exec/Operator.java