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Dynamo is a set of techniques that together can form a highly available key-value structured storage system [1] or a distributed data store. [1] It has properties of both databases and distributed hash tables (DHTs). It was created to help address some scalability issues that Amazon.com's website experienced during the holiday season of 2004. [2] By 2007, it was used in Amazon Web Services, such as its Simple Storage Service (S3). [1]
Amazon DynamoDB is "built on the principles of Dynamo" [3] and is a hosted service within the AWS infrastructure. However, while Dynamo is based on leaderless replication, DynamoDB uses single-leader replication. [4]
Problem | Technique | Advantage |
---|---|---|
Dataset partitioning | Consistent Hashing | Incremental, possibly linear scalability in proportion to the number of collaborating nodes. |
Highly available writes | Vector Clock or Dotted-Version-Vector Sets, reconciliation during reads | Version size is decoupled from update rates. |
Handling temporary failures | Sloppy Quorum and Hinted Handoff | Provides high availability and durability guarantee when some of the replicas are not available. |
Recovering from permanent failures | Anti-entropy using Merkle tree | Can be used to identify differences between replica owners and synchronize divergent replicas pro-actively. |
Membership and failure detection | Gossip-based membership protocol and failure detection | Avoids having a centralized registry for storing membership and node liveness information, preserving symmetry. |
Amazon published the paper on Dynamo, but never released its implementation. The index layer of Amazon S3 implements and extends many core features of Dynamo. Since then, several implementations have been created based on the paper. The paper also inspired many other NoSQL database implementations, such as Apache Cassandra, Project Voldemort and Riak. [2]
MySQL is an open-source relational database management system (RDBMS). Its name is a combination of "My", the name of co-founder Michael Widenius's daughter, and "SQL", the abbreviation for Structured Query Language. A relational database organizes data into one or more data tables in which data types may be related to each other; these relations help structure the data. SQL is a language programmers use to create, modify and extract data from the relational database, as well as control user access to the database. In addition to relational databases and SQL, an RDBMS like MySQL works with an operating system to implement a relational database in a computer's storage system, manages users, allows for network access and facilitates testing database integrity and creation of backups.
Db2 is a family of data management products, including database servers, developed by IBM. They initially supported the relational model, but were extended to support object–relational features and non-relational structures like JSON and XML. The brand name was originally styled as DB/2, then DB2 until 2017 and finally changed to its present form.
A distributed data store is a computer network where information is stored on more than one node, often in a replicated fashion. It is usually specifically used to refer to either a distributed database where users store information on a number of nodes, or a computer network in which users store information on a number of peer network nodes.
In computing, a solution stack or software stack is a set of software subsystems or components needed to create a complete platform such that no additional software is needed to support applications. Applications are said to "run on" or "run on top of" the resulting platform.
Multi-master replication is a method of database replication which allows data to be stored by a group of computers, and updated by any member of the group. All members are responsive to client data queries. The multi-master replication system is responsible for propagating the data modifications made by each member to the rest of the group and resolving any conflicts that might arise between concurrent changes made by different members.
Amazon SimpleDB is a distributed database written in Erlang by Amazon.com. It is used as a web service in concert with Amazon Elastic Compute Cloud (EC2) and Amazon S3 and is part of Amazon Web Services. It was announced on December 13, 2007.
Apache Cassandra is a free and open-source, distributed, wide-column store, NoSQL database management system designed to handle large amounts of data across many commodity servers, providing high availability with no single point of failure. Cassandra offers support for clusters spanning multiple datacenters, with asynchronous masterless replication allowing low latency operations for all clients. Cassandra was designed to implement a combination of Amazon's Dynamo distributed storage and replication techniques combined with Google's Bigtable data and storage engine model.
A NoSQL database provides a mechanism for storage and retrieval of data that is modeled in means other than the tabular relations used in relational databases. Such databases have existed since the late 1960s, but the name "NoSQL" was only coined in the early 21st century, triggered by the needs of Web 2.0 companies. NoSQL databases are increasingly used in big data and real-time web applications. NoSQL systems are also sometimes called "Not only SQL" to emphasize that they may support SQL-like query languages or sit alongside SQL databases in polyglot-persistent architectures.
Couchbase Server, originally known as Membase, is an open-source, distributed multi-model NoSQL document-oriented database software package optimized for interactive applications. These applications may serve many concurrent users by creating, storing, retrieving, aggregating, manipulating and presenting data. In support of these kinds of application needs, Couchbase Server is designed to provide easy-to-scale key-value or JSON document access with low latency and high sustained throughput. It is designed to be clustered from a single machine to very large-scale deployments spanning many machines.
Amazon Relational Database Service is a distributed relational database service by Amazon Web Services (AWS). It is a web service running "in the cloud" designed to simplify the setup, operation, and scaling of a relational database for use in applications. Administration processes like patching the database software, backing up databases and enabling point-in-time recovery are managed automatically. Scaling storage and compute resources can be performed by a single API call to the AWS control plane on-demand. AWS does not offer an SSH connection to the underlying virtual machine as part of the managed service.
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 tolerant data replication and automatic data distribution across the cluster for performance and resilience.
A cloud database is a database that typically runs on a cloud computing platform and access to the database is provided as-a-service. There are two common deployment models: users can run databases on the cloud independently, using a virtual machine image, or they can purchase access to a database service, maintained by a cloud database provider. Of the databases available on the cloud, some are SQL-based and some use a NoSQL data model.
Amazon DynamoDB is a fully managed proprietary NoSQL database service that supports key–value and document data structures and is offered by Amazon.com as part of the Amazon Web Services portfolio. DynamoDB exposes a similar data model to and derives its name from Dynamo, but has a different underlying implementation. Dynamo had a multi-leader design requiring the client to resolve version conflicts and DynamoDB uses synchronous replication across multiple data centers for high durability and availability. DynamoDB was announced by Amazon CTO Werner Vogels on January 18, 2012, and is presented as an evolution of Amazon SimpleDB solution.
Oracle NoSQL Database (ONDB) is a NoSQL-type distributed key-value database from Oracle Corporation. It provides transactional semantics for data manipulation, horizontal scalability, and simple administration and monitoring.
Redis Labs is a private computer software company based in Mountain View, California. It provides a database management system marketed as "NoSQL" as open source software or as a service using cloud computing. The company has additional offices in London and Tel Aviv.
Amazon ElastiCache is a fully managed in-memory data store and cache service by Amazon Web Services (AWS). The service improves the performance of web applications by retrieving information from managed in-memory caches, instead of relying entirely on slower disk-based databases. ElastiCache supports two open-source in-memory caching engines: Memcached and Redis.
Amazon DocumentDB is a fully managed proprietary NoSQL database service that supports document data structures and has limited support for MongoDB workloads up to MongoDB version 3.6 and version 4.0. As a document database, Amazon DocumentDB makes it easy to store, query, and index JSON data. Amazon DocumentDB is currently available in 14 AWS regions of AWS.
TiDB is an open-source NewSQL database that supports Hybrid Transactional and Analytical Processing (HTAP) workloads. It is MySQL compatible and can provide horizontal scalability, strong consistency, and high availability. It is developed and supported primarily by PingCAP, Inc. and licensed under Apache 2.0. TiDB drew its initial design inspiration from Google's Spanner and F1 papers.
YugabyteDB is a free and open-source, distributed, relational, NewSQL database management system designed to handle large amounts of data spanning across multiple availability zones and geographic regions while providing single-digit latency, high availability, and no single point of failure.
A distributed SQL database is a single relational database which replicates data across multiple servers. Distributed SQL databases are strongly consistent and most support consistency across racks, data centers, and wide area networks including cloud availability zones and cloud geographic zones. Distributed SQL databases typically use the Paxos or Raft algorithms to achieve consensus across multiple nodes.
Dynamo is not available to users outside of Amazon. Confusingly, AWS offers a hosted database product called DynamoDB, which uses a completely different architecture: it is based on single-leader replication.