@Override
    public long getEstimatedMemorySize() {
      JavaDataModel jdm = JavaDataModel.get();
      long size = 0;
      size += keySerDe == null ? 0 : jdm.object();
      size += valSerDe == null ? 0 : jdm.object();
      size += keySoi == null ? 0 : DEFAULT_OBJECT_INSPECTOR_MEMORY_SIZE;
      size += valSoi == null ? 0 : DEFAULT_OBJECT_INSPECTOR_MEMORY_SIZE;
      size += keyOis == null ? 0 : jdm.arrayList() + keyOis.size() * DEFAULT_OBJECT_INSPECTOR_MEMORY_SIZE;
      size += valOis == null ? 0 : jdm.arrayList() + valOis.size() * DEFAULT_OBJECT_INSPECTOR_MEMORY_SIZE;
      size += keyObjs == null ? 0 : jdm.array() + keyObjs.length * jdm.object();
      size += valObjs == null ? 0 : jdm.array() + valObjs.length * jdm.object();
      size += jdm.primitive1();
      return size;
    }
Get hash value from the key.
ql/src/java/org/apache/hadoop/hive/ql/exec/persistence/MapJoinBytesTableContainer.java