public static int calculateEstimatedMemorySize(int count) {
    // FUTURE: Partitioning not included yet.
    final int longMatchFlagsSize = (count + Long.SIZE - 1) / Long.SIZE;
    int size = 0;
    JavaDataModel jdm = JavaDataModel.get();
    size += jdm.lengthForLongArrayOfSize(longMatchFlagsSize);
    size += jdm.primitive1();
    size += (2 * jdm.object());
    return size;
  }
Record which hash table slot entries had key matches for FULL OUTER MapJoin.
Supports partitioned match trackers for HybridHashTableContainer.
ql/src/java/org/apache/hadoop/hive/ql/exec/persistence/MatchTracker.java