protected void innerPerBatchSetup(VectorizedRowBatch batch) {

    // For join operators that can generate small table results, reset their
    // (target) scratch columns.

    for (int column : smallTableValueColumnMap) {
      ColumnVector smallTableColumn = batch.cols[column];
      smallTableColumn.reset();
    }
  }
Do the per-batch setup for an inner join.
ql/src/java/org/apache/hadoop/hive/ql/exec/vector/mapjoin/VectorMapJoinInnerGenerateResultOperator.java