Non-Relational Database Systems

The world of Web is shifting from relational to non-relational data stores. There are many non-relational data stores -

Cassandra - Cassandra is a highly scalable, eventually consistent, distributed, structured key-value store. Read more

MongoDB - MongoDB isn't a key/value store, it's a document store. PHP module is available. Read more

Apache CouchDB - Apache CouchDB is a document-oriented database that can be queried and indexed in a MapReduce fashion using JavaScript. CouchDB also offers incremental replication with bi-directional conflict detection and resolution. Read more

MemcacheDB - combines the proven BerkeleyDB storage system with a network server that speaks the memcached network protocol so you can create memcahed-like nodes that hold more data than would fit in a traditional RAM-based memcached nodes and be assured that the data is not lost after a reboot. In some respects this is similar to the Tokyo Cabinet and Tokyo Tyrant combination. Read more

Redis - it's a lightweight in-memory key/value store that handles strings, sets, and lists and has an excellent core of features for manipulating those stored data types. Redis also has built-in replication support and the ability to periodically persist the data on disk so that can survive a reboot without major data loss. Read more

Riak - An Open Source Internet-Scale Data Store. Riak is a Dynamo-inspired key/value store that scales predictably and easily. Riak also simplifies development by giving developers the ability to quickly prototype, test, and deploy their applications. Read more

Tokyo Cabinet - Tokyo Cabinet is a library of routines for managing a database. The database is a simple data file containing records, each is a pair of a key and a value. Every key and value is serial bytes with variable length. Both binary data and character string can be used as a key and a value. There is neither concept of data tables nor data types. Records are organized in hash table, B+ tree, or fixed-length array. Read more

Hypertable - Hypertable is a high performance distributed data storage system designed to support applications requiring maximum performance, scalability, and reliability. Read more

Project Voldemort - is a fairly mature system that’s in heavy use at LinkedIn and comes with automatic replication and partitioning. Read more

Amazon SimpleDB - Amazon SimpleDB is a highly available, scalable, and flexible non-relational data store that offloads the work of database administration. Developers simply store and query data items via web services requests, and Amazon SimpleDB does the rest. Read more