A cloud database is a database that typically runs on a cloud computing platform, with access 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. Cloud databases may use either a relational SQL or a NoSQL data model.
Database services handle scalability and high availability, while making the underlying software stack transparent to users.
Deployment models There are two primary methods to run a database on a cloud platform:
Virtual machine image Cloud platforms allow users to purchase virtual machine instances for a limited time, on which a database can be run. Users can upload their own machine image with a database installed or use ready-made machine images that include an optimized installation of a database.
Database-as-a-service (DBaaS) With a database as a service (DBaaS) model, users pay a cloud provider for database services and computing resources, which may reduce the operational overhead needed to develop and manage databases. Users are provided with tools to create and manage database instances, as well as to manage database users. Some cloud providers also offer tools for managing database structures and data. Many cloud providers offer both relational (e.g., Amazon RDS, SQL Server) and NoSQL (e.g., MongoDB, Amazon DynamoDB) databases. DBaaS is a type of software as a service (SaaS).
Architecture and common characteristics Most database services offer web-based consoles that end users can use to provision and configure database instances. Database services routinely include a database-manager component that manages the underlying database instances using a service API. The API is exposed to end users and permits them to perform maintenance and scaling operations on their database instances. The underlying software stack typically includes the operating system, the database, and third-party software used to manage the database. The service provider is responsible for installing, patching, and updating the underlying software stack, as well as ensuring the overall health and performance of the database. Scalability features differ between vendors—some offer auto-scaling, others allow users to scale resources via an API but do not scale automatically. Service providers typically commit to a defined level of high availability (e.g., 99.9% or 99.99%). This is achieved through techniques such as data replication and automatic failover to standby instances.
Data model The design and development of typical systems often use data management and relational databases as key building blocks. Advanced queries expressed in SQL work well with the strict relationships imposed by relational databases. However, relational database technology was not originally designed for use over distributed systems. This limitation has been addressed through clustering enhancements, although some fundamental operations—such as data synchronization—still require complex and expensive protocols.A. Anjomshoaa and A. Tjoa, "How the cloud computing paradigm could shape the future of enterprise information processing", Proceedings of the 13th International Conference on Information Integration and Web-based Applications and Services - iiWAS'11, pp. 7-10, 2011.
Modern relational databases can exhibit poor performance on data-intensive systems. As a result, the NoSQL paradigm has been adopted within database management systems for cloud-based systems.S. Cass, "Designing for the Cloud", MIT Technology Review, 2009. [Online]. Available: https://www.technologyreview.com/s/414090/designing-for-the-cloud/. Retrieved 2016-10-04. NoSQL storage does not require fixed table schemas, and join operations are typically avoided. NoSQL databases have been shown to provide efficient horizontal scalability, high performance, and ease of integration into cloud applications."NoSQL", Wikipedia, 2016. Retrieved 2016-10-04. Additionally, data models that rely on simplified relay algorithms have been employed in data-intensive cloud mapping applications specific to virtual frameworks.
It is also important to differentiate between cloud databases which are relational (SQL) and those that are non-relational (NoSQL).https://docs.microsoft.com/en-us/azure/architecture/data-guide/big-data/non-relational-data Article in 'Microsoft Azure' SQL databases SQL databases can run in the cloud either on virtual machines or as a managed service, depending on the vendor. While SQL databases are generally easy to scale vertically, horizontal scalability presents a greater challenge.
NoSQL databases NoSQL databases are designed to service heavy read/write loads and can scale up and down easily, making them well suited to cloud environments. However, many contemporary applications are built around a relational (SQL) data model, so adopting NoSQL databases often requires significant changes to application code.Ken North, "SQL, NoSQL or SomeSQL?", Dr. Dobb's, Retrieved 2011-11-9.
Some SQL databases have developed NoSQL capabilities, including JSON, binary JSON (e.g. BSON or similar variants), and key-value store data types.
Multi-model databases combine relational and non-relational capabilities, providing a standard SQL interface to users and applications. Native multi-model databases support multiple data models with a single core, facilitating their use in applications built around SQL.
Vendors The following table lists notable database vendors that offer cloud database services, classified by deployment model—machine image or database as a service—and by data model (SQL or NoSQL).
+ Cloud database vendors by deployment and data model Virtual Machine Deployment Database as a Service SQL Data Model EDB Postgres Advanced Server IBM Db2Deploy your database applications and projects on the cloud, IBM.com, Retrieved 2011-9-1 Ingres (database)Chris Kanaracus, "Ingres rolls out cloud database offerings", InfoWorld, Retrieved 2011-8-28. MariaDB"Amazon Web Services Announces Two New Database Services – AWS Database Migration Service and Amazon RDS for MariaDB , Amazon Press Releases, retrieved 2015-11-17"MariaDB Enterprise Cluster + MariaDB MaxScale , Microsoft Azure, retrieved 2015-11-17 MySQL"Running MySQL on Amazon EC2 with EBS (Elastic Block Store), Amazon Web Services, retrieved 2011-11-20 NuoDBSwoyer, Stephen. "NuoDB: A Database for the Cloud." TDWI. Nov. 13, 2012. Retrieved Nov. 26, 2012 Oracle DatabaseAmazon Machine Images - Oracle Database 11g Release 2 (11.2.0.1) Enterprise Edition - 64 Bit , Amazon Web Services, Retrieved 2011-11-9."Oracle Database in the Cloud", Oracle.com, Retrieved 2011-11-9. PostgreSQLChris Kanaracus, "EnterpriseDB Adding New Cloud Option for PostgreSQL Database", PCWorld, retrieved 2011-8-28 SAP HANA YugabyteDB TiDB Amazon Aurora, MySQL-based service Amazon Relational Database Service Clustrix Database as a Service CockroachDB-as-a-ServiceTony Baer, "Cockroach DB introduces a serverless tier", ZDNet.com, Retrieved 2021-12-13. EnterpriseDB Postgres Plus Cloud DatabaseEnterpriseDB#cite note-10 Google Cloud SQL Heroku PostgreSQL as a Service (shared and dedicated database options)"Announcing Heroku PostgreSQL Database Add-on", Heroku Blog, Retrieved 2011-11-9. Microsoft Azure SQL Database (MS SQL)Noel Yuhanna, SQL Azure Raises The Bar On Cloud Databases, Forrester, Retrieved 2011-11-9. Oracle Database Cloud Service SkySQL MariaDB Snowflake Cloud Data Warehouse Xeround Cloud Database*MySQL front-end (*service no longer available)Klint Finley, "7 Cloud-Based Database Services" , ReadWriteWeb, Retrieved 2011-11-9. YugabyteDB TiDB NoSQL Data Model Apache Cassandra on Amazon EC2"Setting up Cassandra in the Cloud ", Cassandra Wiki, Retrieved 2011-11-10. or Google Compute Engine ArangoDB on Amazon EC2, Google Compute or Microsoft Azure" Clusterpoint Database Virtual Box VM"Clusterpoint Database Virtual Box VM Installation Guide ", Clusterpoint, Retrieved 2015-03-08. CouchDB on Amazon EC2"Amazon Machine Images, CouchDB 0.10.x 32 bit Ubuntu", Amazon Web Services, Retrieved 2011-11-10. or Google Cloud Platform EDB Postgres Advanced Server Hadoop on Amazon EC2,"Amazon Machine Image, Hadoop AMI", Amazon Web Services, Retrieved 2011-11-10. Google Cloud Platform, or Rackspace["http://www.rackspace.com/blog/cloud-big-data-platform-limited-availability/ Hadoop at Rackspace] ", Rackspace Big Data Platforms, Retrieved 2014-02-24. MarkLogic on Amazon EC2 or Google Cloud Platform MongoDB on Amazon EC2, Google Compute Engine or Microsoft Azure, VMware, KVM, and other hypervisors. Neo4J on Amazon EC2"Neo4J in the Cloud ", Neo4J Wiki, Retrieved 2011-11-10. or Microsoft Azure"Announcing Neo4J on Windows Azure", Neo4J Blog, Retrieved 2011-11-10. ScyllaDB on Amazon EC2 or Google Cloud PlatformAdrian Bridgwater, "ScyllaDB's real-time NoSQL database tapped by 'super app'", Computerworld, Retrieved 2012-12-27. YugabyteDB Amazon DynamoDB Amazon SimpleDB Azure Cosmos DB Couchbase Capella Database as a Service Cloudant Data LayerAndrew Brust, "Cloudant Makes NoSQL as a Service Bigger", ZDNet, Retrieved 2012-5-22. (CouchDB) DataStax Astra DB powered by Apache Cassandra EnterpriseDB Postgres Plus Cloud Database Google Cloud Bigtable Google Cloud Datastore MongoDB Database as a Service (several options) Oracle NoSQL Database Cloud Service ScyllaDB Cloud Amazon DocumentDB YugabyteDB
See also Cloud computing Cloud storage Data as a service Relational database
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