A query language, also known as data query language or database query language (DQL), is a computer language used to make queries in databases and information systems. In database systems, query languages rely on strict theory to retrieve information. A well known example is the Structured Query Language (SQL).
JSON is an open standard file format and data interchange format that uses human-readable text to store and transmit data objects consisting of attribute–value pairs and arrays. It is a common data format with diverse uses in electronic data interchange, including that of web applications with servers.
Apache CouchDB is an open-source document-oriented NoSQL database, implemented in Erlang.
A document-oriented database, or document store, is a computer program and data storage system designed for storing, retrieving and managing document-oriented information, also known as semi-structured data.
Freebase was a large collaborative knowledge base consisting of data composed mainly by its community members. It was an online collection of structured data harvested from many sources, including individual, user-submitted wiki contributions. Freebase aimed to create a global resource that allowed people to access common information more effectively. It was developed by the American software company Metaweb and run publicly beginning in March 2007. Metaweb was acquired by Google in a private sale announced on 16 July 2010. Google's Knowledge Graph is powered in part by Freebase.
A graph database (GDB) is a database that uses graph structures for semantic queries with nodes, edges, and properties to represent and store data. A key concept of the system is the graph. The graph relates the data items in the store to a collection of nodes and edges, the edges representing the relationships between the nodes. The relationships allow data in the store to be linked together directly and, in many cases, retrieved with one operation. Graph databases hold the relationships between data as a priority. Querying relationships is fast because they are perpetually stored in the database. Relationships can be intuitively visualized using graph databases, making them useful for heavily inter-connected data.
Redis is an open-source in-memory storage, used as a distributed, in-memory key–value database, cache and message broker, with optional durability. Because it holds all data in memory and because of its design, Redis offers low-latency reads and writes, making it particularly suitable for use cases that require a cache. Redis is the most popular NoSQL database, and one of the most popular databases overall. Redis is used in companies like Twitter, Airbnb, Tinder, Yahoo, Adobe, Hulu, Amazon and OpenAI.
Neo4j is a graph database management system developed by Neo4j, Inc.
FlockDB was an open-source distributed, fault-tolerant graph database for managing wide but shallow network graphs. It was initially used by Twitter to store relationships between users, e.g. followings and favorites. FlockDB differs from other graph databases, e.g. Neo4j in that it was not designed for multi-hop graph traversal but rather for rapid set operations, not unlike the primary use-case for Redis sets. FlockDB was posted on GitHub shortly after Twitter released its Gizzard framework, which it used to query the FlockDB distributed datastore. The database is licensed under the Apache License.
Apache Hive is a data warehouse software project built on top of Apache Hadoop for providing data query and analysis. Hive gives an SQL-like interface to query data stored in various databases and file systems that integrate with Hadoop. Traditional SQL queries must be implemented in the MapReduce Java API to execute SQL applications and queries over distributed data. Hive provides the necessary SQL abstraction to integrate SQL-like queries (HiveQL) into the underlying Java without the need to implement queries in the low-level Java API. Since most data warehousing applications work with SQL-based querying languages, Hive aids the portability of SQL-based applications to Hadoop. While initially developed by Facebook, Apache Hive is used and developed by other companies such as Netflix and the Financial Industry Regulatory Authority (FINRA). Amazon maintains a software fork of Apache Hive included in Amazon Elastic MapReduce on Amazon Web Services.
RethinkDB is a free and open-source, distributed document-oriented database originally created by the company of the same name. The database stores JSON documents with dynamic schemas, and is designed to facilitate pushing real-time updates for query results to applications. Initially seed funded by Y Combinator in June 2009, the company announced in October 2016 that it had been unable to build a sustainable business and its products would in future be entirely open-sourced without commercial support.
ArangoDB is a graph database system developed by ArangoDB Inc. ArangoDB is a multi-model database system since it supports three data models with one database core and a unified query language AQL. AQL is mainly a declarative language and allows the combination of different data access patterns in a single query.
RocksDB is a high performance embedded database for key-value data. It is a fork of Google's LevelDB optimized to exploit multi-core processors (CPUs), and make efficient use of fast storage, such as solid-state drives (SSD), for input/output (I/O) bound workloads. It is based on a log-structured merge-tree data structure. It is written in C++ and provides official language bindings for C++, C, and Java. Many third-party language bindings exist. RocksDB is free and open-source software, released originally under a BSD 3-clause license. However, in July 2017 the project was migrated to a dual license of both Apache 2.0 and GPLv2 license. This change helped its adoption in Apache Software Foundation's projects after blacklist of the previous BSD+Patents license clause.
GraphQL is an open-source data query and manipulation language for APIs and a query runtime engine.
DBeaver is a SQL client software application and a database administration tool. For relational databases it uses the JDBC application programming interface (API) to interact with databases via a JDBC driver. For other databases (NoSQL) it uses proprietary database drivers. It provides an editor that supports code completion and syntax highlighting. It provides a plug-in architecture that allows users to modify much of the application's behavior to provide database-specific functionality or features that are database-independent. This is a desktop application written in Java and based on Eclipse platform.
Shapes Constraint Language (SHACL) is a World Wide Web Consortium (W3C) standard language for describing Resource Description Framework (RDF) graphs. SHACL has been designed to enhance the semantic and technical interoperability layers of ontologies expressed as RDF graphs.
Prometheus is a free software application used for event monitoring and alerting. It records metrics in a time series database built using an HTTP pull model, with flexible queries and real-time alerting. The project is written in Go and licensed under the Apache 2 License, with source code available on GitHub, and is a graduated project of the Cloud Native Computing Foundation, along with Kubernetes and Envoy.
Blazegraph is an open source triplestore and graph database, developed by Systap, which is used in the Wikidata SPARQL endpoint and by other large customers. It is licensed under the GNU GPL.
Datacommons.org is an open knowledge graph hosted by Google that provides a unified view across multiple public datasets, combining economic, scientific and other open datasets into an integrated data graph. The Datacommons.org site was launched in May 2018 with an initial dataset consisting of fact-checking data published in Schema.org "ClaimReview" format by several fact checkers from the International Fact-Checking Network. Google has worked with partners including the United States Census, the World Bank, and US Bureau of Labor Statistics to populate the repository, which also hosts data from Wikipedia, the National Oceanic and Atmospheric Administration and the Federal Bureau of Investigation. The service expanded during 2019 to include an RDF-style Knowledge Graph populated from a number of largely statistical open datasets. The service was announced to a wider audience in 2019. In 2020 the service improved its coverage of non-US datasets, while also increasing its coverage of bioinformatics and coronavirus.
Ontotext GraphDB is a graph database and knowledge discovery tool compliant with RDF and SPARQL and available as a high-availability cluster. Ontotext GraphDB is used in various European research projects.
