Consistent Range-Queries in DistributedKey-Value Stores : Providing Consistent Range-Query Operations for the CATS NoSQL Database

Sammanfattning: Big Data is data that is too large for storage in traditional relationaldatabases. Recently, NoSQL databases have emerged as a suitable platformfor the storage of Big Data. Most of them, such as Dynamo, HBase, andCassandra, sacrifice consistency for scalability. They provide eventual dataconsistency guarantees, which, can make the application logic complicated fordevelopers. In this master thesis project we use CATS; a scalable and partitiontolerant Key-Value store offering strong data consistency guarantees. Itmeans that the value read is, in some sense, the latest value written. We havedesigned and evaluated a lightweight range-query mechanism for CATS, that,provides strong consistency for all returned data items. Our solution reuses themechanism already available in CATS for data consistency. Using this solutionCATS can guarantee strong data consistency for both lookup queries andrange-queries. This enables us to build new classes of applications using CATS.Our range-query solution has been used to build a high level data model, whichsupports secondary indexes, on top of CATS.