Hybrid transactional/analytical processing (HTAP)

HTAPHTAP databases
HTAP functionality is offered by database companies, such as Alibaba DRDS, TiDB, Hubble, ArangoDB, Aerospike, Apache Ignite/GridGain In-Memory Data Fabric, IBM IBM_Db2 IDAA, InterSystems, Kdb+, Microsoft SQL Server, Neo4j, Oracle 12c In-Memory, SAP HANA]], MemSQL, MongoDB, VoltDB, NuoDB, OrientDB, DataStax, eXtremeDB, Splice Machine, EsgynDB, Cloud Spanner, HarperDB, Amazon Aurora (Parallel Query) and BlobCity.

List of TCP and UDP port numbers

well-known portportwell-known
This is a list of TCP and UDP port numbers used by protocols of the application layer of the Internet protocol suite for the establishment of host-to-host connectivity.


The tests used the standard YCSB benchmark and the other NoSQL systems were Cassandra, HBase, Oracle NoSQL, Redis, Voldemort, Scalaris, Elasticsearch, MongoDB, and OrientDB. All data is maintained in memory (RAM), with data persistence ensured by write-ahead logging and snapshotting, and for those reasons some industry observers have compared Tarantool to Membase. Replication is asynchronous and failover (getting one Tarantool server to take over from another) is possible either from a replica server or from a "hot standby" server. There are no locks. Tarantool uses Lua-style coroutines and asynchronous I/O.

Operational database

operationaloperational database systemtransactional databases
Operational database management systems (also referred to as OLTP On Line Transaction Processing databases), are used to update data in real-time. These types of databases allow users to do more than simply view archived data. Operational databases allow you to modify that data (add, change or delete data), doing it in real-time. OLTP databases provide transactions as main abstraction to guarantee data consistency that guarantee the so-called ACID properties. Basically, the consistency of the data is guaranteed in the case of failures and/or concurrent access to the data.


Yahoo! Cloud Serving Benchmarks (YCSB)
It has been used for multiple-product comparisons by industry observers such as Network World (comparing Cassandra, MongoDB, and Riak), Thumbtack Technologies (comparing Aerospike, Cassandra, Couchbase, and MongoDB), and the Polytechnic Institute and University of Coimbra (comparing Cassandra, HBase, Elasticsearch, MongoDB, Oracle NoSQL, OrientDB, Redis, Scalaris, Tarantool, and Voldemort). SanDisk Corporation published results measured on the Oracle NoSQL Database.

Comparison of structured storage software

Structured storage is computer storage for structured data, often in the form of a distributed database. Computer software formally known as structured storage systems include Apache Cassandra, Google's Bigtable and Apache HBase.

Cloud database

Database as a ServiceCloudcloud data
A cloud database is a database that typically runs on a cloud computing platform, and access to the database is provided as-a-service.

AQL (ArangoDB Query Language)

AQL is the SQL-like query language used in the ArangoDB database management system. It supports CRUD operations for both documents (nodes) and edges, but it is not a data definition language (DDL). AQL does support geospatial queries. AQL is JSON-oriented as illustrated by the following query, which also illustrates the intuitive "dot" notation for accessing the values of keys: FOR x IN [{"a": {"A":1}}, {"a": {"A": 2}}] FILTER x.a.A < 2 RETURN x.a The following is a parameterized query for finding the number of descendants of a particular node in a graph named with nodes: FOR v IN 1 ..

Couchbase, Inc.

Couchbase, Inc. is a private software company that develops and provides commercial packages and support for Couchbase Server and Couchbase Lite both of which are open-source, NoSQL, multi-model, document-oriented database that store JSON documents or a pure key-value database. The company has its headquarters in Santa Clara, California and offices in San Francisco, Bangalore and the United Kingdom. NorthScale was founded in 2009, and in March 2010 announced $5 million in funding from Accel Partners and North Bridge Venture Partners. Original officers listed were James Phillips, Steve Yen and Dustin Sallings, who were involved in the development of memcached.

Apache CouchDB

In early 2012, Katz left the project to focus on Couchbase Server. Since Katz's departure, the Apache CouchDB project has continued, releasing 1.2 in April 2012 and 1.3 in April 2013. In July 2013, the CouchDB community merged the codebase for BigCouch, Cloudant's clustered version of CouchDB, into the Apache project. The BigCouch clustering framework is included in the current release of Apache CouchDB. Native clustering is supported at version 2.0.0. And the new Mango Query Server provides a simple JSON-based way to perform CouchDB queries without JavaScript or MapReduce. CouchDB also offers a built-in administration interface accessible via Web called Futon.


Couchbase Server. Redis. Mnesia. MemcacheDB. Hazelcast. Cassandra. Tarantool. Ehcache.


Altoros is an active contributor to other open source initiatives, such as Couchbase Server (a distributed NoSQL document-oriented database) and Cloud Foundry (a platform-as-a-service system). Starting from 2012, Altoros regularly issues independent technology benchmarks that help to evaluate performance of open source big data technologies, such as Hadoop and NoSQL systems (MongoDB, Couchbase, Cassandra, Redis, etc.). Since 2014, Altoros is a Silver Member of the Cloud Foundry Foundation (governed by the Linux Foundation ). Prior to joining this initiative, the Altoros team contributed to the Cloud Foundry Community Advisory Board meetings on a monthly basis.

Go (programming language)

GoGo programming languageGolang
Couchbase, Query and Indexing services within the Couchbase Server. Dropbox, who migrated some of their critical components from Python to Go. Ethereum, a cryptocurrency. Google, for many projects, notably including download server dl.google.com. Heroku, for Doozer, a lock service. Hyperledger Fabric, an open source, enterprise-focused distributed ledger project. MongoDB, tools for administering MongoDB instances. Netflix, for two portions of their server architecture. Novartis, for an internal inventory system. Nutanix, for a variety of micro-services in its Enterprise Cloud OS. Plug.dj, an interactive online social music streaming website.


TLA + TLA+ specification language
Microsoft Azure used TLA + to design Cosmos DB, a globally-distributed database with five different consistency models. A key-value store with snapshot isolation A rule-based firewall A multi-car elevator system State - an assignment of values to variables. Behaviour - a sequence of states. Step - a pair of successive states in a behavior. Stuttering step - a step during which variables are unchanged. Next-state relation - a relation describing how variables can change in any step. State function - an expression containing variables and constants that is not a next-state relation.

Shared-nothing architecture

shared-nothingshared nothing architectureshared nothing
A shared-nothing architecture (SN) is a distributed-computing architecture in which each node is independent and self-sufficient, and there is no single point of contention across the system. More specifically, none of the nodes share memory or disk storage. People typically contrast SN with systems that keep a large amount of centrally-stored state information, whether in a database, an application server, or any other similar single point of contention.

Time to live

TTLtime-to-livehop limit
Time to live (TTL) or hop limit is a mechanism that limits the lifespan or lifetime of data in a computer or network. TTL may be implemented as a counter or timestamp attached to or embedded in the data. Once the prescribed event count or timespan has elapsed, data is discarded or revalidated. In computer networking, TTL prevents a data packet from circulating indefinitely. In computing applications, TTL is commonly used to improve the performance and manage the caching of data.

Concurrent user

concurrent usersCCUsconcurrent player count
In computer science, the number of concurrent users for a resource in a location, with the location being a computing network or a single computer, refers to the total number of people using the resource within a predefined period of time. The resource can, for example, be a computer program, a file, or the computer as a whole.

Object database

object-oriented databaseobject-oriented databasesobject-oriented
An object database is a database management system in which information is represented in the form of objects as used in object-oriented programming. Object databases are different from relational databases which are table-oriented. Object-relational databases are a hybrid of both approaches.

Range query (database)

range queryrange queriesrange
A range query is a common database operation that retrieves all records where some value is between an upper and lower boundary. For example, list all employees with 3 to 5 years' experience. Range queries are unusual because it is not generally known in advance how many entries a range query will return, or if it will return any at all. Many other queries, such as the top ten most senior employees, or the newest employee, can be done more efficiently because there is an upper bound to the number of results they will return. A query that returns exactly one result is sometimes called a singleton.

Persistence (computer science)

persistencepersistentpersistent storage
In computer science, persistence refers to the characteristic of state that outlives the process that created it. This is achieved in practice by storing the state as data in computer data storage. Programs have to transfer data to and from storage devices and have to provide mappings from the native programming-language data structures to the storage device data structures.

Spatial query

spatial queries
A spatial query is a special type of database query supported by geodatabases and spatial databases. The queries differ from non-spatial SQL queries in several important ways. Two of the most important are that they allow for the use of geometry data types such as points, lines and polygons and that these queries consider the spatial relationship between these geometries.


B+ treeB+ treesB-
In computer science, a B-tree is a self-balancing tree data structure that maintains sorted data and allows searches, sequential access, insertions, and deletions in logarithmic time. The B-tree is a generalization of a binary search tree in that a node can have more than two children. Unlike self-balancing binary search trees, the B-tree is well suited for storage systems that read and write relatively large blocks of data, such as discs. It is commonly used in databases and file systems.


The term "software multitenancy" refers to a software architecture in which a single instance of software runs on a server and serves multiple tenants. A tenant is a group of users who share a common access with specific privileges to the software instance. With a multitenant architecture, a software application is designed to provide every tenant a dedicated share of the instance - including its data, configuration, user management, tenant individual functionality and non-functional properties. Multitenancy contrasts with multi-instance architectures, where separate software instances operate on behalf of different tenants.