@Override
  public void evaluate(VectorizedRowBatch batch) throws HiveException {

    // return immediately if batch is empty
    final int n = batch.size;
    if (n == 0) {
      return;
    }

    if (childExpressions != null) {
      super.evaluateChildren(batch);
    }

    ColumnVector outV = batch.cols[outputColumnNum];
    MapColumnVector mapV = (MapColumnVector) batch.cols[inputColumnNum[0]];
    // indexColumnVector includes the keys of Map
    indexColumnVector = batch.cols[inputColumnNum[1]];
    ColumnVector valuesV = mapV.values;

    int[] sel = batch.selected;
    boolean[] indexIsNull = indexColumnVector.isNull;
    boolean[] mapIsNull = mapV.isNull;
    boolean[] outputIsNull = outV.isNull;

    // We do not need to do a column reset since we are carefully changing the output.
    outV.isRepeating = false;

    /*
     * Do careful maintenance of the outputColVector.noNulls flag.
     */

    if (indexColumnVector.isRepeating) {

      /*
       * Repeated index or repeated NULL index.
       */
      if (indexColumnVector.noNulls || !indexIsNull[0]) {

        /*
         * Same INDEX for entire batch.
         */
        if (mapV.isRepeating) {
          if (mapV.noNulls || !mapIsNull[0]) {
            final int repeatedMapIndex = findInMap(indexColumnVector, 0, mapV, 0);
            if (repeatedMapIndex == -1) {
              outV.isNull[0] = true;
              outV.noNulls = false;
            } else {
              outV.isNull[0] = false;
              outV.setElement(0, repeatedMapIndex, valuesV);
            }
          } else {
            outputIsNull[0] = true;
            outV.noNulls = false;
          }
          outV.isRepeating = true;
          return;
        }

        /*
         * Individual row processing for LIST vector with *repeated* INDEX value.
         */
        if (mapV.noNulls) {
          if (batch.selectedInUse) {

            // CONSIDER: For large n, fill n or all of isNull array and use the tighter ELSE loop.

            if (!outV.noNulls) {
              for (int j = 0; j < n; j++) {
                final int i = sel[j];
                final int mapIndex = findInMap(indexColumnVector, 0, mapV, i);
                if (mapIndex == -1) {
                  outV.isNull[i] = true;
                  outV.noNulls = false;
                } else {
                  outV.isNull[i] = false;
                  outV.setElement(i, mapIndex, valuesV);
                }
              }
            } else {
              for (int j = 0; j < n; j++) {
                final int i = sel[j];
                final int mapIndex = findInMap(indexColumnVector, 0, mapV, i);
                if (mapIndex == -1) {
                  outV.isNull[i] = true;
                  outV.noNulls = false;
                } else {
                  outV.setElement(i, mapIndex, valuesV);
                }
              }
            }
          } else {
            if (!outV.noNulls) {

              // Assume it is almost always a performance win to fill all of isNull so we can
              // safely reset noNulls.
              Arrays.fill(outputIsNull, false);
              outV.noNulls = true;
            }
            for (int i = 0; i < n; i++) {
              final int mapIndex = findInMap(indexColumnVector, 0, mapV, i);
              if (mapIndex == -1) {
                outV.isNull[i] = true;
                outV.noNulls = false;
              } else {
                outV.setElement(i, mapIndex, valuesV);
              }
            }
          }
        } else /* there are NULLs in the LIST */ {

          if (batch.selectedInUse) {
            for (int j=0; j != n; j++) {
              int i = sel[j];
              if (!mapIsNull[i]) {
                final int mapIndex = findInMap(indexColumnVector, 0, mapV, i);
                if (mapIndex == -1) {
                  outV.isNull[i] = true;
                  outV.noNulls = false;
                } else {
                  outV.isNull[i] = false;
                  outV.setElement(i, mapIndex, valuesV);
                }
              } else {
                outputIsNull[i] = true;
                outV.noNulls = false;
              }
            }
          } else {
            for (int i = 0; i != n; i++) {
              if (!mapIsNull[i]) {
                final int mapIndex = findInMap(indexColumnVector, 0, mapV, i);
                if (mapIndex == -1) {
                  outV.isNull[i] = true;
                  outV.noNulls = false;
                } else {
                  outV.isNull[i] = false;
                  outV.setElement(i, mapIndex, valuesV);
                }
              } else {
                outputIsNull[i] = true;
                outV.noNulls = false;
              }
            }
          }
        }
      } else {
        outputIsNull[0] = true;
        outV.noNulls = false;
        outV.isRepeating = true;
      }
      return;
    }

    // ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

    /*
     * Same MAP instance for entire batch.
     *
     * (Repeated INDEX case handled above).
     */

    if (mapV.isRepeating) {
      if (mapV.noNulls || !mapIsNull[0]) {

        /*
         * Individual row processing for INDEX vector with *repeated* MAP instance.
         */

        if (indexColumnVector.noNulls) {
          if (batch.selectedInUse) {

             // CONSIDER: For large n, fill n or all of isNull array and use the tighter ELSE loop.

             if (!outV.noNulls) {
               for (int j = 0; j != n; j++) {
                 final int i = sel[j];
                 final int mapIndex = findInMap(indexColumnVector, i, mapV, 0);
                 if (mapIndex == -1) {
                   outV.isNull[i] = true;
                   outV.noNulls = false;
                 } else {
                   outV.isNull[i] = false;
                   outV.setElement(i, mapIndex, valuesV);
                 }
               }
             } else {
               for (int j = 0; j != n; j++) {
                 final int i = sel[j];
                 final int mapIndex = findInMap(indexColumnVector, i, mapV, 0);
                 if (mapIndex == -1) {
                   outV.isNull[i] = true;
                   outV.noNulls = false;
                 } else {
                   outV.setElement(i, mapIndex, valuesV);
                 }
               }
             }
          } else {
            if (!outV.noNulls) {

              // Assume it is almost always a performance win to fill all of isNull so we can
              // safely reset noNulls.
              Arrays.fill(outputIsNull, false);
              outV.noNulls = true;
            }
            for (int i = 0; i != n; i++) {
              final int mapIndex = findInMap(indexColumnVector, i, mapV, 0);
              if (mapIndex == -1) {
                outV.isNull[i] = true;
                outV.noNulls = false;
              } else {
                outV.setElement(i, mapIndex, valuesV);
              }
            }
          }
        } else /* there are NULLs in the inputColVector */ {

          /*
           * Do careful maintenance of the outV.noNulls flag.
           */

          if (batch.selectedInUse) {
            for(int j=0; j != n; j++) {
              int i = sel[j];
              if (!indexIsNull[i]) {
                final int mapIndex = findInMap(indexColumnVector, i, mapV, 0);
                if (mapIndex == -1) {
                  outV.isNull[i] = true;
                  outV.noNulls = false;
                } else {
                  outV.isNull[i] = false;
                  outV.setElement(i, mapIndex, valuesV);
                }
              } else {
                outputIsNull[i] = true;
                outV.noNulls = false;
              }
            }
          } else {
            for(int i = 0; i != n; i++) {
              if (!indexIsNull[i]) {
                final int mapIndex = findInMap(indexColumnVector, i, mapV, 0);
                if (mapIndex == -1) {
                  outV.isNull[i] = true;
                  outV.noNulls = false;
                } else {
                  outV.isNull[i] = false;
                  outV.setElement(i, mapIndex, valuesV);
                }
              } else {
                outputIsNull[i] = true;
                outV.noNulls = false;
              }
            }
          }
        }
      } else {
        outputIsNull[0] = true;
        outV.noNulls = false;
        outV.isRepeating = true;
      }
      return;
    }

    // ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

    /*
     * Individual row processing for INDEX vectors and LIST vectors.
     */
    final boolean listNoNulls = mapV.noNulls;

    if (indexColumnVector.noNulls) {
      if (batch.selectedInUse) {

         // CONSIDER: For large n, fill n or all of isNull array and use the tighter ELSE loop.

         if (!outV.noNulls) {
           for (int j = 0; j != n; j++) {
             final int i = sel[j];

             if (listNoNulls || !mapIsNull[i]) {
               final int mapIndex = findInMap(indexColumnVector, i, mapV, i);
               if (mapIndex == -1) {
                 outV.isNull[i] = true;
                 outV.noNulls = false;
               } else {
                 outV.isNull[i] = false;
                 outV.setElement(i, mapIndex, valuesV);
               }
             } else {
               outputIsNull[i] = true;
               outV.noNulls = false;
             }
           }
         } else {
           for (int j = 0; j != n; j++) {
             final int i = sel[j];
             if (listNoNulls || !mapIsNull[i]) {
               final int mapIndex = findInMap(indexColumnVector, i, mapV, i);
               if (mapIndex == -1) {
                 outV.isNull[i] = true;
                 outV.noNulls = false;
               } else {
                 outV.setElement(i, mapIndex, valuesV);
               }
             } else {
               outputIsNull[i] = true;
               outV.noNulls = false;
             }
           }
         }
      } else {
        if (!outV.noNulls) {

          // Assume it is almost always a performance win to fill all of isNull so we can
          // safely reset noNulls.
          Arrays.fill(outputIsNull, false);
          outV.noNulls = true;
        }
        for (int i = 0; i != n; i++) {
          if (listNoNulls || !mapIsNull[i]) {
            final int mapIndex = findInMap(indexColumnVector, i, mapV, i);
            if (mapIndex == -1) {
              outV.isNull[i] = true;
              outV.noNulls = false;
            } else {
              outV.setElement(i, mapIndex, valuesV);
            }
          } else {
            outputIsNull[i] = true;
            outV.noNulls = false;
          }
        }
      }
    } else /* there are NULLs in the inputColVector */ {

      /*
       * Do careful maintenance of the outV.noNulls flag.
       */

      if (batch.selectedInUse) {
        for(int j=0; j != n; j++) {
          int i = sel[j];
          if (!indexIsNull[i]) {
            if (listNoNulls || !mapIsNull[i]) {
              final int mapIndex = findInMap(indexColumnVector, i, mapV, i);
              if (mapIndex == -1) {
                outV.isNull[i] = true;
                outV.noNulls = false;
              } else {
                outV.isNull[i] = false;
                outV.setElement(i, mapIndex, valuesV);
              }
            } else {
              outputIsNull[i] = true;
              outV.noNulls = false;
            }
          } else {
            outputIsNull[i] = true;
            outV.noNulls = false;
          }
        }
      } else {
        for(int i = 0; i != n; i++) {
          if (!indexIsNull[i]) {
            if (listNoNulls || !mapIsNull[i]) {
              final int mapIndex = findInMap(indexColumnVector, i, mapV, i);
              if (mapIndex == -1) {
                outV.isNull[i] = true;
                outV.noNulls = false;
              } else {
                outV.isNull[i] = false;
                outV.setElement(i, mapIndex, valuesV);
              }
            } else {
              outputIsNull[i] = true;
              outV.noNulls = false;
            }
          } else {
            outputIsNull[i] = true;
            outV.noNulls = false;
          }
        }
      }
    }
  }
Superclass to support vectorized functions that take a column value as key of Map
and return the value of Map.
ql/src/java/org/apache/hadoop/hive/ql/exec/vector/expressions/VectorUDFMapIndexBaseCol.java