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A NoSQL or Not Only SQL database provides a mechanism for storage and retrieval of data that is modeled in means other than the tabular relations used in relational databases. Motivations for this approach include simplicity of design, horizontal scaling and finer control over availability. The data structure (e.g., tree, graph, key-value) differs from the RDBMS, and therefore some operations are faster in NoSQL and some in RDBMS. There are differences though and the particular suitability of a given NoSQL DB depends on the problem to be solved (e.g., does the solution use tree algorithms?). The appearance of mature NoSQL databases has reduced the rationale for Java content repository (JCR) implementations.

NoSQL databases are finding significant and growing industry use in big data and real-time web applications.[1] NoSQL systems are also referred to as "Not only SQL" to emphasize that they may in fact allow SQL-like query languages to be used. In the context of the CAP theorem, NoSQL stores often compromise consistency in favor of availability and partition tolerance. Barriers to the greater adoption of NoSQL data stores in practice include: the lack of full ACID transaction support, the use of low-level query languages, the lack of standardized interfaces, and the huge investments already made in SQL by enterprises. [2]


Carlo Strozzi used the term NoSQL in 1998 to name his lightweight, open-source relational database that did not expose the standard SQL interface.[3] Strozzi suggests that, as the current NoSQL movement "departs from the relational model altogether; it should therefore have been called more appropriately 'NoREL'.[4]

Eric Evans reintroduced the term NoSQL in early 2009 when Johan Oskarsson of wanted to organize an event to discuss open-source distributed databases.[5] The name attempted to label the emergence of a growing number of non-relational, distributed data stores that often did not attempt to provide atomicity, consistency, isolation and durability guarantees that are key attributes of classic relational database systems.[6]


There have been various approaches to classify NoSQL databases, each with different categories and subcategories. Because of the variety of approaches and overlaps it is difficult to get and maintain an overview of non-relational databases. Nevertheless, the basic classification that most would agree on is based on data model. A few of these and their prototypes are:

Classification based on data model[edit]

Stephen Yen in his blog post "NoSQL is a Horseless Carriage" suggests the following:[7]

TermMatching Database
KV CacheCoherence, eXtreme Scale, GigaSpaces, Hazelcast, Infinispan, JBoss Cache, Memcached, Repcached, Terracotta, Velocity
KV StoreFlare, Keyspace, RAMCloud, SchemaFree
KV Store - Eventually consistentDovetailDB, Dynamo, Dynomite, MotionDb, Voldemort, SubRecord
Data-structures serverRedis
KV Store - OrderedActord, Lightcloud, Luxio, MemcacheDB, NMDB, Scalaris, TokyoTyrant
Tuple StoreApache River, Coord, GigaSpaces
Object DatabaseDB4O, Perst, Shoal, ZopeDB,
Document StoreClusterpoint, CouchDB, MarkLogic, MongoDB, Riak, XML-databases
Wide Columnar StoreBigTable, Cassandra, HBase, Hypertable, KAI, KDI, OpenNeptune, Qbase

Classification based on feature[edit]

Ben Scofield categorized NoSQL databases based on nonfunctional categories (“(il)ities“) plus a rating of their feature coverage:[citation needed]

Data ModelPerformanceScalabilityFlexibilityComplexityFunctionality
Key–value Storeshighhighhighmoderateassociative array
Column Storehighhighmoderatelowcolumnar database
Document Storehighvariable (high)highlowobject model, based on document object model or markup language
Graph Databasevariablevariablehighhighgraph theory
Relational Databasevariablevariablelowmoderaterelational algebra


Document store[edit]

The central concept of a document store is the notion of a "document". While each document-oriented database implementation differs on the details of this definition, in general, they all assume that documents encapsulate and encode data (or information) in some standard formats or encodings. Encodings in use include XML, YAML, and JSON as well as binary forms like BSON, PDF and Microsoft Office documents (MS Word, Excel, and so on).

Different implementations offer different ways of organizing and/or grouping documents:

Compared to relational databases, for example, collections could be considered analogous to tables and documents analogous to records. But they are different: every record in a table has the same sequence of fields, while documents in a collection may have fields that are completely different.

Documents are addressed in the database via a unique key that represents that document. One of the other defining characteristics of a document-oriented database is that, beyond the simple key-document (or key–value) lookup that you can use to retrieve a document, the database will offer an API or query language that will allow retrieval of documents based on their contents.

BaseXJava, XQueryXML database
CloudantC, Erlang, Java, ScalaJSON store (online service)
ClusterpointC, C++, REST, XML, full text searchXML database with spport for JSON, text, binaries
Couchbase ServerC, C++, ErlangSupport for JSON and binary documents
Apache CouchDBErlangJSON database
djondb[8][9][10]C++JSON, ACID Document Store
SolrJavaSearch engine
ElasticSearchJavaJSON, Search engine
eXistJava, XQueryXML database
JackrabbitJavaJava Content Repository implementation
IBM Notes and IBM DominoLotusScript, Java, IBM X Pages, othersMultiValue
MarkLogic ServerJava, REST, XQueryXML database with support for JSON, text, and binaries
MongoDBC++, C#, GoBSON store (binary format JSON)
ObjectDatabase++C++, C#, TScriptBinary Native C++ class structures
Oracle NoSQL DatabaseC, Java
OrientDBJavaJSON, SQL support
CoreFoundation Property listC, C++, Objective-CJSON, XML, binary
SednaC++, XQueryXML database
SimpleDBErlangonline service
TokuMXC++, C#, GoMongoDB with Fractal Tree indexing
OpenLink VirtuosoC++, C#, Java, SPARQLmiddleware and database engine hybrid


This kind of database is designed for data whose relations are well represented as a graph (elements interconnected with an undetermined number of relations between them). The kind of data could be social relations, public transport links, road maps or network topologies, for example.

AllegroGraphSPARQLRDF GraphStore
DEX/SparkseeC++, Java, .NET, PythonHigh-performance graph database
IBM DB2SPARQLRDF GraphStore added in DB2 10
InfiniteGraphJavaHigh-performance, scalable, distributed graph database
OWLIMJava, SPARQL 1.1RDF graph store with reasoning
Sones GraphDBC#
Sqrrl EnterpriseJavaDistributed, real-time graph database featuring cell-level security
OpenLink VirtuosoC++, C#, Java, SPARQLmiddleware and database engine hybrid

Key–value stores[edit]

Key–value stores allow the application to store its data in a schema-less way. The data could be stored in a datatype of a programming language or an object. Because of this, there is no need for a fixed data model.[11][12] The following types exist:

KV - eventually consistent[edit]

KV - hierarchical[edit]

KV - cache in RAM[edit]

KV - solid state or rotating disk[edit]

KV - ordered[edit]

Object database[edit]


Tuple store[edit]

Triple/Quad Store (RDF) database[edit]


Multivalue databases[edit]

Cell database[edit]

NoSQL databases on the cloud[edit]

NoSQL databases can be run on-premises, but are also often run on IaaS or PaaS platforms like Amazon Web Services, RackSpace or Heroku. There are three common deployment models for NoSQL on the cloud:

The following table provides notable examples of NoSQL databases available on the cloud in each of these deployment models:

Deployment ModelDatabase TechnologyProviderCloud-Specific FeaturesPricing Model
Native cloud NoSQL databaseAmazon SimpleDBAmazon Web Services
  • Managed service
  • High availability
  • Unlimited scale
  • Data durability
  • Free for 750 hours on micro instance[15]
  • Pay per use - separate charge for machine utilization and data usage[15]
Virtual machine imageCassandraApache Cassandra - machine image for Amazon EC2[16]None
  • Database and machine image - open source
  • Amazon instances - pay per use
Database as a ServiceCassandraInstaclustr[17] - available on Amazon EC2, RackSpace, Windows Azure, Joyent, Google Compute Engine
  • Managed service
  • Performance tuning
  • Monitoring
  • Automated backups
  • DataStax OpsCenter for cluster administration

Paid plans based on disk storage, memory usage and CPU cores[18]

Native cloud NoSQL databaseGoogle App Engine Datastore[19]Google
  • No planned downtime
  • Atomic transactions
  • High availability of reads and writes
  • Free with quota system limiting instance hours, storage and throughput[20]
  • Pay per use based on instance hours, storage, throughput and other parameters
Virtual machine imageMongoDBMongoDB - machine images for Amazon EC2[21] and Windows Azure[22]None
  • Database and machine image - open source
  • Amazon/Azure instances - pay per use
Database as a ServiceMongoDBMongoLab[23] - available on Amazon, Google, Joyent, Rackspace and Windows Azure
  • Managed service
  • High availability
  • Automatic failover
  • Pre-configured clustering
  • Free up to 500MB (on disk)[24]
  • Paid plans based on architecture and storage size
Database as a ServiceRedis/MemcachedAmazon Web Services - ElastiCache[25]
  • Managed service
  • Automatic healing of failed nodes
  • Resilient system to prevent overloaded DBs
  • Performance monitoring
  • Free for 750 hours on micro instance[26]
  • Pay per use for machine utilization, no separate charge for data usage[27]
Virtual Machine ImageRedis
  • Redis - standard open source installation
  • Script for installation on Amazon EC2 [28]
  • Recommended installation on Windows Azure [29]
  • Database and machine image - open source
  • Amazon/Azure instances - pay per use
Database as a ServiceRedisRedisToGo[30] - available on Amazon EC2, RackSpace, Heroku, AppHarbor, Orchestra
  • Managed service
  • Daily backups
  • API enabling creation, deletion, or download of Redis instances
  • Free up to 5MB (memory)
  • Paid plans based on memory usage
Database as a ServiceRedisRedis Cloud (Redis Labs)[31] - available on Amazon EC2, Windows Azure, Heroku, Cloud Foundry, OpenShift, AppFog, AppHarbor
  • Managed service
  • Automatic scaling, unlimited Redis nodes
  • High availability
  • Built-in clustering
  • Free up to 25MB (memory)[32]
  • Pay per use
Native cloud NoSQL databaseSalesForce[33]SalesForce
  • Unlimited scale
  • Access to SalesForce meta data
  • Social API
  • Support for mobile clients
  • Multi-tenancy
  • Free up to 100K records and 50K transactions[34]
  • Pay per use based on users, number of records and transactions

See also[edit]


  1. ^ "RDBMS dominate the database market, but NoSQL systems are catching up". 21 Nov 2013. Retrieved 24 Nov 2013. 
  2. ^ K. Grolinger, W.A. Higashino, A. Tiwari, M.A.M. Capretz (2013). "Data management in cloud environments: NoSQL and NewSQL data stores". JoCCASA, Springer. Retrieved 8 Jan 2014. 
  3. ^ Lith, Adam; Jakob Mattson (2010). "Investigating storage solutions for large data: A comparison of well performing and scalable data storage solutions for real time extraction and batch insertion of data" (PDF). Göteborg: Department of Computer Science and Engineering, Chalmers University of Technology. p. 70. Retrieved 12 May 2011. "Carlo Strozzi first used the term NoSQL in 1998 as a name for his open source relational database that did not offer a SQL interface[...]" 
  4. ^ "NoSQL Relational Database Management System: Home Page". 2 October 2007. Retrieved 29 March 2010. 
  5. ^ "NoSQL 2009". 12 May 2009. Retrieved 29 March 2010. 
  6. ^ Mike Chapple. "The ACID Model". 
  7. ^ A Yes for a NoSQL Taxonomy. High Scalability (2009-11-05). Retrieved on 2013-09-18.
  8. ^ The enterprise class NoSQL database. djondb. Retrieved on 2013-09-18.
  9. ^
  10. ^ Undefined Blog: Meeting with DjonDB. Retrieved on 2013-09-18.
  11. ^ Sandy (14 January 2011). "Key Value stores and the NoSQL movement". Stackexchange. Retrieved 1 January 2012. "Key–value stores allow the application developer to store schema-less data. This data usually consists of a string that represents the key, and the actual data that is considered to be the value in the "key–value" relationship. The data itself is usually some kind of primitive of the programming language (a string, an integer, or an array) or an object that is being marshaled by the programming language's bindings to the key–value store. This structure replaces the need for a fixed data model and allows proper formatting." 
  12. ^ Marc Seeger (21 September 2009). "Key-Value Stores: a practical overview". Marc Seeger. Retrieved 1 January 2012. "Key–value stores provide a high-performance alternative to relational database systems with respect to storing and accessing data. This paper provides a short overview of some of the currently available key–value stores and their interface to the Ruby programming language." 
  13. ^ "Riak: An Open Source Scalable Data Store". 28 November 2010. Retrieved 28 November 2010 * OpenLink Virtuoso
  14. ^ Tweed, Rob; George James (2010). "A Universal NoSQL Engine, Using a Tried and Tested Technology" (PDF). p. 25. "Without exception, the most successful and well-known of the NoSQL databases have been developed from scratch, all within just the last few years. Strangely, it seems that nobody looked around to see whether there were any existing, successfully implemented database technologies that could have provided a sound foundation for meeting Web-scale demands. Had they done so, they might have discovered two products, GT.M and Caché.....*" 
  15. ^ a b Amazon SimpleDB Pricing, Amazon Web Services, Retrieved 2013-12-29.
  16. ^ "Setting up Cassandra in the Cloud", Cassandra Wiki, Retrieved 2011-11-10.
  17. ^ "Instaclustr Managed Apache Cassandra Hosting",, Retrieved 2013-12-29.
  18. ^ Instaclustr Providers & Pricing,, Retrieved 2013-12-29.
  19. ^ "Java Datastore API", Google App Engine, Retrieved 2013-12-29.
  20. ^ App Engine Pricing, Google Cloud Platform, Retrieved 2013-12-29.
  21. ^ "Neo4J in the Cloud", Neo4J Wiki, Retrieved 2011-11-10.
  22. ^ "MongoDB on Azure,, Retrieved 2011-11-10.
  23. ^ "MongoLab Product Overview",, Retrieved 2013-12-29.
  24. ^ "MongoLab Plans and Pricing",, Retrieved 2013-12-29.
  25. ^ "Amazon ElastiCache", Amazon Web Services, Retrieved 2013-12-29.
  26. ^ "Amazon ElastiCache Free Usage Tier", Amazon Web Services, Retrieved 2013-12-29.
  27. ^ "Amazon ElastiCache Pricing", Amazon Web Services, Retrieved 2013-12-29.
  28. ^ "Install", GitHub Gist, Retrieved 2013-12-29.
  29. ^ "Running Redis on a CentOS Linux VM in Windows Azure", Thomas Conté's MSDN Weblog, Retrieved 2013-12-29.
  30. ^ "RedisToGo Documentation",, Retrieved 2013-12-29.
  31. ^ Redis Cloud by Redis Labs,, Retrieved 2013-12-29.
  32. ^ "Garantia Data Pricing",, Retrieved 2013-12-29.
  33. ^ "How it works",, Retrieved 2013-12-29.
  34. ^ " Pricing",, Retrieved 2013-12-29.

Further reading[edit]

External links[edit]