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    An overview of Couchbase Server’s core features.

    Core Features

    This section provides descriptions of Couchbase Server’s core features. The descriptions are organized as follows:

    • Data: Couchbase Server stores data as items. Each item consists of a key, by which the item is referenced; and an associated value, which must be either binary or a JSON document.

      See Data for information.

    • Buckets, Memory, and Storage: Items are stored in named Buckets; being kept only in memory, others both in memory and on disk.

      See Buckets, Memory, and Storage for information.

    • Services and Indexes: Services can be deployed to support different forms of data-access: for example, the Data Service allows items to be retrieved by key; while the Query Service allows them to be retrieved by means of queries, designed in the N1QL query-language. Individual services can be configured to run across multiple cluster-nodes, allowing high-priority workloads to be distributed and scaled appropriately. Indexes support services, by enabling high-performance access to data.

      See Services and Indexes for information.

    • Clusters and Availability: A single node running Couchbase Server is considered a cluster of one node. As successive nodes are initialized, each can be configured to join the existing cluster.

      Across the nodes of each cluster, Couchbase data is evenly distributed and replicated: nodes can be removed, and node-failure handled, without data-loss. Data can be selected for replication across clusters residing in different data centers, to ensure high availability.

      See Clusters and Availability for information.

    Couchbase Glossary

    The following glossary introduces the principal terms used in descriptions of Couchbase Server-technology. Use the links to locate the full descriptions of each.

    • Server: An instance of Couchbase Server — an open source, distributed, NoSQL document-oriented engagement database, specialized to provide low-latency data management for large-scale interactive web, mobile, and other applications. Each instance runs on its on physical or virtual machine.

    • Cluster: One or more instances of Couchbase Server, each running on an independent node; but cooperating with any and all others, so as to form a unified system; whereby resources are shared, and a single interface provided for data-access and management.

    • Bucket: A logical, user-named entity that groups items; allowing them to be accessed, indexed, replicated, and access-controlled. There are three types:

      • Couchbase: Retains data both in memory and on disk.

      • Ephemeral: Retains data in memory only.

      • Memcached: Designed to be used in the context of other database platforms, such as ones employing relational database technology, in order to provide a managed memory-cache for frequently-used data.

    • Memory: An automatically managed caching layer, supporting high-speed data-access.

    • Storage: The persistent retention of items on disk, in compressed form, with high-speed threaded access.

    • Data: Items, each of which consists of a key by which the item is referenced; and an associated value, which must be either binary or a JSON document.

      • Access: The creation, update, and deletion of items, as supported by the Couchbase Web Console UI and the Couchbase SDK.

      • Model: A lightweight, flexible schema; which can be progressively evolved by applications over time, and allows information to be stored in the form of items.

    • Node: A computer (potentially, a virtual machine) running an instance of Couchbase Server.

      • Addition: The ability to add a Couchbase Cluster of one node to another existing cluster, so that a single, combined cluster is produced. Following addition, rebalance ensures that data and indexes are optimally distributed across all available nodes.

      • Failover: The ability to allow healthy nodes to continue functioning as a cluster, potentially without data-loss, when one node has gone offline. Rebalance ensures that data and indexes are optimally distributed across all available nodes. Failover can be automated.

      • Removal: The ability to remove a node from a cluster. Following removal, rebalance ensures that data and indexes are optimally distributed across all available nodes.

    • Rebalance: The process of redistributing data and indexes optimally among the available nodes of a cluster. This should be performed whenever a cluster-configuration has changed.

    • Availability: The preservation of data from system-failure, by the following means:

      • Backup and Restore: The storing in archive-repositories of the current state of data, indexes, and bucket configurations; and the restoration of such state to a running cluster.

      • Cross Datacenter Replication (XDCR): The replication of data between clusters, to ensure the least chance of data-loss in the event of data-center failure, and to provide high-performance data-access for globally distributed applications.

      • Data Recovery: The restoration of current data to a node that is recovered from failure: either by updating data still held locally, or by substituting current data from other nodes.

      • Intra-Cluster Replication: The maintenance and continuous update of data-copies, distributed across the nodes of a cluster, to ensure the least chance of data-loss in the event of single-node failure.

    • Deployment: The installation of a single instance of Couchbase Server, subsequent to the appropriate resourcing and configuration of an underlying platform.

      • Cloud: Couchbase Server runs on a pre-established cloud-configuration.

      • Container: Couchbase Server runs within a software container or virtual machine.

      • Native: Couchbase Server runs on an individual, physical machine.

    • Initialization: The configuration of a new instance of Couchbase Server, either as the first node in a new cluster, or as an additional node for an existing cluster.

    • Security: Couchbase-Server Authentication, Authorization, Auditing, and Encryption.

      • Authentication: To access Couchbase Server, administrators and applications must be authenticated. Authentication is a process for identifying a user who is attempting to access a system. Authentication can be attempted by passing credentials, or by means of certificates.

      • Authorization: Role-Based Access Control (RBAC), whereby access-privileges are assigned to fixed roles that are themselves assigned to administrators and applications.

      • Auditing: The detailed, automated recording of actions performed on Couchbase Server, allowing administrative review; in order to ensure that system-management tasks are being appropriately performed.

      • Encryption: SSL/TLS, used to encrypt data passed over the wire.

    • Services: Couchbase Server-facilities that support different forms of data-access:

      • Analytics: Supports join, set, aggregation, and grouping operations that are expected to be large, long-running, and highly consumptive of memory and CPU resources.

      • Data: Supports the storing, setting, and retrieving of data-items, specified by key.

      • Eventing: Supports near real-time handling of changes to data: code can be executed both in response to document-mutations, and as scheduled by timers.

      • Index: Creates indexes, for use by the Query and Analytics services.

      • Query: Parses input specified in the N1QL query-language, executes queries, and returns results. The Query Service interacts with both the Data and Index services.

      • Search: Creates indexes specially purposed for Full Text Search. This supports language-aware searching; allowing users to search for, say, the word beauties, and additionally obtain results for beauty and beautiful.

    • Scaling: The optional allocation of services to cluster-nodes in accordance with workload-requirements. For example, if a particular service is expected to handle a heavy workload, it can be allocated a large memory quota, and might be deployed as the only service on its node, to ensure optimal availability of CPU cycles.

    • Tools: Provided by Couchbase Server to support cluster-management:

      • CLI: Command-line-based management.

      • Couchbase Web Console: UI-based management.

      • REST API: RESTful management. Note that the REST API, as well as being directly available to the administrator, also underlies the features of the Couchbase Web Console and CLI.

    • SDK: Libraries that support cluster-access for applications written in Java, .NET, C, Go, PHP, Python, and NodeJs.