1. http://www.comp.nus.edu.sg/~dbsystem/source.html. http://www.comp.nus.edu.sg/~dbsystem/source.html.
2. https://github.com/amplab/spark-indexedrdd. https://github.com/amplab/spark-indexedrdd.
3. Apache accumulo. http://accumulo.apache.org. Apache accumulo. http://accumulo.apache.org.
4. Apache avro project. http://avro.apache.org. Apache avro project. http://avro.apache.org.
5. Apache parquet project. http://parquet.incubator.apache.org. Apache parquet project. http://parquet.incubator.apache.org.