|
Riak is a distributed NoSQL key-value data store that offers high availability, fault tolerance, operational simplicity, and scalability. In addition to the open-source version, it comes in a supported enterprise version and a cloud storage version.〔 Riak implements the principles from Amazon's Dynamo paper with heavy influence from the CAP Theorem. Written in Erlang, Riak has fault tolerance data replication and automatic data distribution across the cluster for performance and resilience. Riak is licensed using a freemium model: open source versions of Riak and Riak CS are available, but end users can pay for additional features and support.〔 Riak has a pluggable backend for its core storage, with the default storage backend being Bitcask.〔(【引用サイトリンク】url=http://docs.basho.com/riak/latest/ops/advanced/backends/bitcask/ )〕 LevelDB is also supported. ==Main features== ;Fault-tolerant availability: Riak replicates key/value stores across a cluster of nodes with a default n_val of three. In the case of node outages due to network partition or hardware failures, data can still be written to a neighboring node beyond the initial three, and read-back due to its "masterless" peer-to-peer architecture. ;Queries: Riak provides a REST-ful API through HTTP and Protocol Buffers for basic PUT, GET, POST, and DELETE functions. More complex queries are also possible, including secondary indexes, search (via Apache Solr), and MapReduce. MapReduce has native support for both JavaScript (using the SpiderMonkey runtime) and Erlang. ;Predictable latency: Riak distributes data across nodes with hashing and can provide latency profile, even in the case of multiple node failures. ;Storage options: Keys/values can be stored in memory, disk, or both. ;Multi-datacenter replication: In multi-datacenter replication, one cluster acts as a "primary cluster." The primary cluster handles replication requests from one or more "secondary clusters" (generally located in other regions or countries). If the datacenter with the primary cluster goes down, a second cluster can take over as the primary cluster. :There are two primary modes of operation: fullsync and realtime. In fullsync mode, a complete synchronization occurs between primary and secondary cluster(s), by default every six hours. In real-time mode,replication to the secondary data center(s) is triggered by updates to the primary data center. All multi-datacenter replication occurs over multiple concurrent TCP connections to maximize performance and network utilization. :Note that multi-datacenter replication is not a part of open source Riak. ;Tunable consistency: Option to choose between eventual and strong consistency for each bucket. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Riak」の詳細全文を読む スポンサード リンク
|