![]() (A shard is a master with one or more replicas.) Alternatively, the shard key can be hashed to map to a shard–enabling an even data distribution. The data is split into ranges (based on the shard key) and distributed across multiple shards. The user chooses a shard key, which determines how the data in a collection will be distributed. MongoDB scales horizontally using sharding. As a consequence, an idealized distributed MongoDB deployment requires at least three separate servers, even in the case of just one primary and one secondary. It has a single responsibility, which is to resolve the election of the new primary. If the replicated MongoDB deployment only has a single secondary member, a separate daemon called an arbiter must be added to the set. Secondaries can optionally serve read operations, but that data is only eventually consistent by default. When a primary replica fails, the replica set automatically conducts an election process to determine which secondary should become the primary. Secondary replicas maintain a copy of the data of the primary using built-in replication. All writes and reads are done on the primary replica by default. Each replica-set member may act in the role of primary or secondary replica at any time. A replica set consists of two or more copies of the data. MongoDB provides high availability with replica sets. Queries can also be configured to return a random sample of results of a given size.įields in a MongoDB document can be indexed with primary and secondary indices or index. Queries can return specific fields of documents and also include user-defined JavaScript functions. MongoDB supports field, range query, and regular-expression searches. Customers can use the managed offering from BABA's global data centers. On October 30, 2019, MongoDB teamed up with Alibaba Cloud, who will offer its customers a MongoDB-as-a-service solution. On Novemwith the stable release 4.0.4 the software's license changed from AGPL 3.0 to SSPL. On October 20, 2017, MongoDB became a publicly traded company, listed on NASDAQ as MDB with an IPO price of $24 per share. ![]() In 2013, 10gen changed its name to MongoDB Inc. ![]() In 2009, the company shifted to an open-source development model, with the company offering commercial support and other services. The US software company 10gen began developing MongoDB in 2007 as a component of a planned platform as a service product. ![]()
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