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Structured storage is computer storage for structured data, often in the form of a distributed database. [1] Computer software formally known as structured storage systems include Apache Cassandra, [2] Google's Bigtable [3] and Apache HBase. [4]
The following is a comparison of notable structured storage systems.
| Project Name | Type | Persistence | Replication | High Availability | Transactions | Rack-locality Awareness | Implementation Language | Influences, Sponsors | License | 
|---|---|---|---|---|---|---|---|---|---|
| Aerospike | NoSQL database | Yes, Hybrid DRAM and flash for persistence | Yes | Yes, Distributed for scale | Yes | Yes | C (small bits of assembly language) | Aerospike | AGPL v3 | 
| AllegroGraph | Graph database | Yes | No - v5, 2010 | Yes | Yes | No | Common Lisp | Franz Inc. | Proprietary | 
| Apache Ignite | Key-value | To and from an underlying persistent storage (e.g. an RDBMS) | Yes | Yes | Yes | Yes | Java | Apache, GridGain Systems | Apache 2.0 | 
| Apache Jackrabbit | Key-value & Hierarchical & Document | Yes | Yes | Yes | Yes | likely | Java | Apache, Roy Fielding, Day Software | Apache 2.0 | 
| Berkeley DB/Dbm 1.x | Key-value | Yes | No | No | No | No | C | old school | Various | 
| Berkeley DB Sleepycat/Oracle Berkeley DB 5.x | Key-value | Yes | Yes | Yes | Yes | No | C, C++, or Java | dbm, Sleepycat/Oracle | dual GPL-like Sleepycat License | 
| Apache Cassandra | Key-value | Yes | Yes | Distributed | Partial Only supports CAS (Check And Set) after 2.1.1 and later [5] [6] | Yes | Java | Dynamo and Bigtable, Facebook/Digg/Rackspace | Apache 2.0 | 
| ClustrixDB | scale-out relational | Yes | Yes | Distributed and Replication | Yes | No | C | Clustrix | Proprietary | 
| Coherence | Key-value | Persistent data typically in an RDBMS | Yes | Yes | Yes | Yes | Java | Oracle (previously Tangosol) | Proprietary | 
| Oracle NoSQL Database | Key-value | Yes | Yes | Yes | Yes | No | Java | Oracle | AGPLv3 License or proprietary | 
| Couchbase | Document | Yes | Yes | Yes | Yes, with two-phase commits [7] | Yes | C++, Erlang, C, [8] Go | CouchDB, Memcached | Apache 2.0 | 
| CouchDB | Document | Yes | Yes | replication + load balancing | Atomicity is per document, per CouchDB instance [9] | No | Erlang | Lotus Notes / Ubuntu, Mozilla, IBM | Apache 2.0 | 
| Extensible Storage Engine(ESE/NT) | Document or Key-value | Yes | No | No | Yes | No | C++, Assembly | Microsoft | Proprietary | 
| FoundationDB | Ordered Key-value | Yes | Yes | Yes | Yes | Depends on user configuration | C++ | FoundationDB | Proprietary | 
| GT.M | Key-value | Yes | Yes | Yes | Yes | Depends on user configuration | C (small bits of assembly language) | FIS | AGPL v3 | 
| Project Name | Type | Persistence | Replication | High Availability | Transactions | Rack-locality Awareness | Implementation Language | Influences, Sponsors | License | 
| Apache HBase | Key-value | Yes. Major version upgrades require re-import. | Yes HDFS, [10] Amazon S3 [11] or Amazon Elastic Block Store. [12] | Yes [13] | Yes [14] | See HDFS, S3 or EBS. | Java | Bigtable | Apache 2.0 | 
| Information Management System IBM IMS aka DB1 | Key-value. Multi-level | Yes | Yes | Yes, with HALDB | Yes, with IMS TM | Unknown | Assembler | IBM since 1966 | Proprietary | 
| Infinispan | Key-value | Yes | Yes | Yes | Yes | Yes | Java | Red Hat | Apache 2.0 | 
| Memcached | Key-value | No | No | No | Partial Only supports CAS (Check And Set - or Compare And Swap) [15] [16] | No | C | Six Apart/Couchbase/Fotolog/Facebook | BSD-like permissive copyright by Danga | 
| LevelDB | Key-value, Bigtable | Yes | No | No | Partial Multiple writes can be combined into single operation | No | C++ | New BSD License | |
| LightningDB | Key-value, memory-mapped files | Yes | No | No | Yes, ACID, MVCC | No | C | Symas | OpenLDAP Public License | 
| MongoDB | Document (JSON) | Yes | Yes | fail-over | Partial Single document atomicity [17] | No | C++ | 10gen | GNU AGPL v3.0 | 
| Neo4j | Graph database | Yes | Yes | Yes | Yes | No | Java | Neo Technology | GNU GPL v3.0 | 
| OrientDB | Multi-Model (Graph-Document-Object-Key/Value) | Yes | Yes [18] | Yes [19] | Yes [20] | Yes | Java | Orient Technologies | Apache 2.0 | 
| Redis | Key-value | Yes. But last few queries can be lost. [21] | Yes | Yes [22] | Yes [23] | No | Ansi-C | VMWare, Memcache | BSD | 
| ScyllaDB | Key-value | Yes | Yes | Distributed and Replication [24] | No [25] | Unknown | C++ | Apache Cassandra | AGPL v3 | 
| SimpleDB (Amazon.com) | Document & Key-value | Yes | Yes (automatic) | Yes | Unknown | likely | Erlang | Amazon.com | Amazon internal only | 
| Tarantool | Free-dimensional tuples with primary and secondary keys | Yes. (Asynchronous) | Yes | Yes | Yes | No | C, Lua [26] | Memcached, Mnesia, MySQL, Mail.ru | BSD | 
| Project Name | Type | Persistence | Replication | High Availability | Transactions | Rack-locality Awareness | Implementation Language | Influences, Sponsors | License | 
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