This article has multiple issues. Please help improve it or discuss these issues on the talk page . (Learn how and when to remove these template messages)
|
Original author(s) | Avinash Lakshman, Prashant Malik / Facebook |
---|---|
Developer(s) | Apache Software Foundation |
Initial release | July 2008 |
Stable release | |
Repository | |
Written in | Java |
Operating system | Cross-platform |
Available in | English |
Type | NoSQL Database, data store |
License | Apache License 2.0 |
Website | cassandra |
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 data centers, [2] 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. [3]
Avinash Lakshman, one of the authors of Amazon's Dynamo, and Prashant Malik initially developed Cassandra at Facebook to power the Facebook inbox search feature. Facebook released Cassandra as an open-source project on Google code in July 2008. [4] In March 2009, it became an Apache Incubator project. [5] On February 17, 2010, it graduated to a top-level project. [6]
Facebook developers named their database after the Trojan mythological prophet Cassandra, with classical allusions to a curse on an oracle. [7]
Releases after graduation include
Version | Original release date | Latest version | Release date | Status [16] |
---|---|---|---|---|
0.6 | 2010-04-12 | 0.6.13 | 2011-04-18 | No longer maintained |
0.7 | 2011-01-10 | 0.7.10 | 2011-10-31 | No longer maintained |
0.8 | 2011-06-03 | 0.8.10 | 2012-02-13 | No longer maintained |
1.0 | 2011-10-18 | 1.0.12 | 2012-10-04 | No longer maintained |
1.1 | 2012-04-24 | 1.1.12 | 2013-05-27 | No longer maintained |
1.2 | 2013-01-02 | 1.2.19 | 2014-09-18 | No longer maintained |
2.0 | 2013-09-03 | 2.0.17 | 2015-09-21 | No longer maintained |
2.1 | 2014-09-16 | 2.1.22 | 2020-08-31 | No longer maintained |
2.2 | 2015-07-20 | 2.2.19 | 2020-11-04 | No longer maintained |
3.0 | 2015-11-09 | 3.0.29 | 2023-05-15 | Maintained until 5.0.0 release (Nov-Dec 2023) |
3.11 | 2017-06-23 | 3.11.15 | 2023-05-05 | Maintained until 5.0.0 release (Nov-Dec 2023) |
4.0 | 2021-07-26 | 4.0.9 | 2023-04-14 | Maintained until 5.1.0 release (~July 2024) |
4.1 | 2022-06-17 | 4.1.4 | 2024-02-14 | Latest release |
Legend: Old version Older version, still maintained Latest version Latest preview version |
Cassandra introduced the Cassandra Query Language (CQL). CQL is a simple interface for accessing Cassandra, as an alternative to the traditional Structured Query Language (SQL). CQL adds an abstraction layer that hides implementation details of this structure and provides native syntaxes for collections and other common encodings. Language drivers are available for Java (JDBC), Python (DBAPI2), Node.JS (Datastax), Go (gocql) and C++. [21]
The keyspace in Cassandra is a namespace that defines data replication across nodes. Therefore, replication is defined at the keyspace level. Below an example of keyspace creation, including a column family in CQL 3.0: [22]
CREATEKEYSPACEMyKeySpaceWITHREPLICATION={'class':'SimpleStrategy','replication_factor':3};USEMyKeySpace;CREATECOLUMNFAMILYMyColumns(idtext,lastNametext,firstNametext,PRIMARYKEY(id));INSERTINTOMyColumns(id,lastName,firstName)VALUES('1','Doe','John');SELECT*FROMMyColumns;
Which gives:
id | lastName | firstName ----+----------+---------- 1 | Doe | John (1 rows)
Up to Cassandra 1.0, Cassandra was not row-level consistent, [23] meaning that inserts and updates into the table that affect the same row that are processed at approximately the same time may affect the non-key columns in inconsistent ways. One update may affect one column while another affects the other, resulting in sets of values within the row that were never specified or intended. Cassandra 1.1 solved this issue by introducing row-level isolation. [24]
Cassandra is not supported on Windows as of version 4, see issue CASSANDRA-16171. [25]
Deletion markers called "Tombstones" are known to cause severe performance degradation. [26]
Cassandra is wide column store, and, as such, essentially a hybrid between a key-value and a tabular database management system. Its data model is a partitioned row store with tunable consistency. [19] Rows are organized into tables; the first component of a table's primary key is the partition key; within a partition, rows are clustered by the remaining columns of the key. [27] Other columns may be indexed separately from the primary key. [28]
Tables may be created, dropped, and altered at run-time without blocking updates and queries. [29]
Cassandra cannot do joins or subqueries. Rather, Cassandra emphasizes denormalization through features like collections. [30]
A column family (called "table" since CQL 3) resembles a table in an RDBMS (Relational Database Management System). Column families contain rows and columns. Each row is uniquely identified by a row key. Each row has multiple columns, each of which has a name, value, and a timestamp. Unlike a table in an RDBMS, different rows in the same column family do not have to share the same set of columns, and a column may be added to one or multiple rows at any time. [31]
Each key in Cassandra corresponds to a value which is an object. Each key has values as columns, and columns are grouped together into sets called column families. Thus, each key identifies a row of a variable number of elements. These column families could be considered then as tables. A table in Cassandra is a distributed multi dimensional map indexed by a key. Furthermore, applications can specify the sort order of columns within a Super Column or Simple Column family.
Cassandra is a Java-based system that can be managed and monitored via Java Management Extensions (JMX). The JMX-compliant nodetool utility, for instance, can be used to manage a Cassandra cluster (adding nodes to a ring, draining nodes, decommissioning nodes, and so on). [32] Nodetool also offers a number of commands to return Cassandra metrics pertaining to disk usage, latency, compaction, garbage collection, and more. [33]
Since Cassandra 2.0.2 in 2013, measures of several metrics are produced via the Dropwizard metrics framework, [34] and may be queried via JMX using tools such as JConsole or passed to external monitoring systems via Dropwizard-compatible reporter plugins. [35]
PostgreSQL, also known as Postgres, is a free and open-source relational database management system (RDBMS) emphasizing extensibility and SQL compliance. PostgreSQL features transactions with atomicity, consistency, isolation, durability (ACID) properties, automatically updatable views, materialized views, triggers, foreign keys, and stored procedures. It is supported on all major operating systems, including Linux, FreeBSD, OpenBSD, macOS, and Windows, and handles a range of workloads from single machines to data warehouses or web services with many concurrent users.
MySQL Cluster is a technology providing shared-nothing clustering and auto-sharding for the MySQL database management system. It is designed to provide high availability and high throughput with low latency, while allowing for near linear scalability. MySQL Cluster is implemented through the NDB or NDBCLUSTER storage engine for MySQL.
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.
SAP IQ is a column-based, petabyte scale, relational database software system used for business intelligence, data warehousing, and data marts. Produced by Sybase Inc., now an SAP company, its primary function is to analyze large amounts of data in a low-cost, highly available environment. SAP IQ is often credited with pioneering the commercialization of column-store technology.
Solr is an open-source enterprise-search platform, written in Java. Its major features include full-text search, hit highlighting, faceted search, real-time indexing, dynamic clustering, database integration, NoSQL features and rich document handling. Providing distributed search and index replication, Solr is designed for scalability and fault tolerance. Solr is widely used for enterprise search and analytics use cases and has an active development community and regular releases.
Apache CouchDB is an open-source document-oriented NoSQL database, implemented in Erlang.
A database shard, or simply a shard, is a horizontal partition of data in a database or search engine. Each shard is held on a separate database server instance, to spread load.
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 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.
Hector is a high-level client API for Apache Cassandra. Named after Hector, a warrior of Troy in Greek mythology, it is a substitute for the Cassandra Java Client, or Thrift, that is encapsulated by Hector. It also has Maven repository access.
A keyspace in a NoSQL data store is an object that holds together all column families of a design. It is the outermost grouping of the data in the data store. It resembles the schema concept in Relational database management systems. Generally, there is one keyspace per application.
The standard column family is a NoSQL object that contains columns of related data. It is a tuple (pair) that consists of a key–value pair, where the key is mapped to a value that is a set of columns. In analogy with relational databases, a standard column family is as a "table", each key–value pair being a "row". Each column is a tuple consisting of a column name, a value, and a timestamp. In a relational database table, this data would be grouped together within a table with other non-related data.
A tombstone is a deleted record in a replica of a distributed data store. The tombstone is necessary, as distributed data stores use eventual consistency, where only a subset of nodes where the data is stored must respond before an operation is considered to be successful.
Apache Accumulo is a highly scalable sorted, distributed key-value store based on Google's Bigtable. It is a system built on top of Apache Hadoop, Apache ZooKeeper, and Apache Thrift. Written in Java, Accumulo has cell-level access labels and server-side programming mechanisms. According to DB-Engines ranking, Accumulo is the third most popular NoSQL wide column store behind Apache Cassandra and HBase and the 67th most popular database engine of any type (complete) as of 2018.
Apache Drill is an open-source software framework that supports data-intensive distributed applications for interactive analysis of large-scale datasets. Built chiefly by contributions from developers from MapR, Drill is inspired by Google's Dremel system. Drill is an Apache top-level project. Tom Shiran is the founder of the Apache Drill Project. It was designated an Apache Software Foundation top-level project in December 2016.
Oracle NoSQL Database 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.
FoundationDB is a free and open-source multi-model distributed NoSQL database developed by Apple Inc. with a shared-nothing architecture. The product was designed around a "core" database, with additional features supplied in "layers." The core database exposes an ordered key–value store with transactions. The transactions are able to read or write multiple keys stored on any machine in the cluster while fully supporting ACID properties. Transactions are used to implement a variety of data models via layers.
Apache Trafodion is an open-source Top-Level Project at the Apache Software Foundation. It was originally developed by the information technology division of Hewlett-Packard Company and HP Labs to provide the SQL query language on Apache HBase targeting big data transactional or operational workloads. The project was named after the Welsh word for transactions. As of April 2021, it is no longer actively developed.
A wide-column store is a column-oriented DBMS and therefore a special type of NoSQL database. It uses tables, rows, and columns, but unlike a relational database, the names and format of the columns can vary from row to row in the same table. A wide-column store can be interpreted as a two-dimensional key–value store. Google's Bigtable is one of the prototypical examples of a wide-column store.
Presto is a distributed query engine for big data using the SQL query language. Its architecture allows users to query data sources such as Hadoop, Cassandra, Kafka, AWS S3, Alluxio, MySQL, MongoDB and Teradata, and allows use of multiple data sources within a query. Presto is community-driven open-source software released under the Apache License.
Trino is an open-source distributed SQL query engine designed to query large data sets distributed over one or more heterogeneous data sources. Trino can query data lakes that contain open column-oriented data file formats like ORC or Parquet residing on different storage systems like HDFS, AWS S3, Google Cloud Storage, or Azure Blob Storage using the Hive and Iceberg table formats. Trino also has the ability to run federated queries that query tables in different data sources such as MySQL, PostgreSQL, Cassandra, Kafka, MongoDB and Elasticsearch. Trino is released under the Apache License.
Cassandra's innate datacenter concepts are important as they allow multiple workloads to be run across multiple datacenters…
Apache Cassandra is named after the Greek mythological prophet Cassandra. [...] Because of her beauty Apollo granted her the ability of prophecy. [...] When Cassandra of Troy refused Apollo, he put a curse on her so that all of her and her descendants' predictions would not be believed. [...] Cassandra is the cursed Oracle[.]