Mongodb
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| Developer(s) | MongoDB Inc. |
|---|---|
| Initial release | 2009 |
| Stable release |
3.4.2 / 1 February 2017
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| Preview release |
3.5.2 / 26 January 2017
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| Repository | github |
| Development status | Active |
| Written in | C++, C and JavaScript |
| Operating system | Windows Vista and later, Linux, OS X 10.7 and later, Solaris,FreeBSD |
| Available in | English |
| Type | Document-oriented database |
| License | Various; see § Licensing |
| Website | www |
MongoDB (from humongous) is a free and open-source cross-platform document-oriented database program. Classified as a NoSQL database program, MongoDB uses JSON-like documents with schemas. MongoDB is developed by MongoDB Inc. and is free and open-source, published under a combination of the GNU Affero General Public License and the Apache License.
The software company 10gen began developing MongoDB in 2007 as a component of a planned platform as a service product. In 2009, the company shifted to an open source development model, with the company offering commercial support and other services. In 2013, 10gen changed its name to MongoDB Inc.
MongoDB supports field, range queries, regular expression searches. Queries can return specific fields of documents and also include user-defined JavaScript functions. Queries can also be configured to return a random sample of results of a given size.
Fields in a MongoDB document can be indexed with primary and secondary indices.
MongoDB provides high availability with replica sets. A replica set consists of two or more copies of the data. Each replica set member may act in the role of primary or secondary replica at any time. All writes and reads are done on the primary replica by default. Secondary replicas maintain a copy of the data of the primary using built-in replication. When a primary replica fails, the replica set automatically conducts an election process to determine which secondary should become the primary. Secondaries can optionally serve read operations, but that data is only eventually consistent by default.
MongoDB scales horizontally using sharding. The user chooses a shard key, which determines how the data in a collection will be distributed. The data is split into ranges (based on the shard key) and distributed across multiple shards. (A shard is a master with one or more slaves.). Alternatively, the shard key can be hashed to map to a shard – enabling an even data distribution.
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Wikipedia