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MyISAM
MyISAM was the default storage engine for the MySQL relational database management system versions prior to 5.5 released in December 2009. It is based on the older ISAM code, but it has many useful extensions. Filesystem Each MyISAM table is stored on disk in three files (if it is not partitioned). The files have names that begin with the table name and have an extension to indicate the file type. MySQL uses a .frm file to store the definition of the table, but this file is not a part of the MyISAM engine; instead it is a part of the server. The data file has a .MYD (MYData) extension. The index file has a .MYI (MYIndex) extension. The index file, if lost, can always be recreated by recreating indexes. Files format depends on the ROW_FORMAT table option. The following formats are available: * FIXED: Fixed is a format where all data (including variable-length types) have a fixed length. This format is faster to read, and improves corrupted tables repair. If a table contains big ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aria (storage Engine)
Aria is a storage engine for the MariaDB and MySQL relational database management systems. Its goal is to make a crash-safe alternative to MyISAM. It is not transactional. Aria has been in development since 2007 and was first announced by Michael "Monty" Widenius on his blog. Aria is used for internal temporary tables in MariaDB, a community-developed branch of the MySQL database led by Widenius. Aria is not shipped with MySQL or Percona Server. The Maria project is hosted on Launchpad. Aria was initially named "Maria", as a reference to Monty's youngest child. It was renamed Aria in 2010 to avoid confusion with the main database it is developed for, MariaDB. Chris Tooley, who won a contest to suggest the name, wrote, "Aria is Maria without the 'M'; also it is a pleasant musical term." Features Aria is very similar to MyISAM, but its purpose is to be a crash-safe alternative to MyISAM. Aria does not support foreign keys and, currently, transactions. Aria supports: * Ful ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Comparison Of MySQL Database Engines ...
This is a comparison between notable database engines for the MySQL database management system (DBMS). A database engine (or "storage engine") is the underlying software component that a DBMS uses to create, read, update and delete (CRUD) data from a database. External links MySQL Documentation on MyISAM Storage EngineMyISAM's open files limit and table-cache problem explainedThe article about problems which will occur in using MyISAM {{MySQL Database engines MySQL MySQL MySQL () is an open-source relational database management system (RDBMS). Its name is a combination of "My", the name of co-founder Michael Widenius's daughter My, and "SQL", the acronym for Structured Query Language. A relational database o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Virtual Column
In relational databases a virtual column is a table column whose value is automatically computed using other columns values, or another deterministic expression. Virtual columns are defined of SQL:2003 as Generated Column, and are only implemented by some DBMSs, like MariaDB, SQL Server, Oracle, PostgreSQL, SQLite and Firebird (database server) (COMPUTED BY syntax). Implementation There are two types of virtual columns: * Virtual columns; * Persistent columns. Virtual columns values are computed ''on the fly'' when needed, for example when they are returned by a SELECT statement. Persistent column values are computed when a row is inserted in a table, and they are written like all other values. They can change if other values change. Both virtual and persistent columns have advantages and disadvantages: virtual columns don't consume space on the disk, but they must be computed every time a query refers to them; persistent columns don't require any CPU time, but they consume dis ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Database Engine
A database engine (or storage engine) is the underlying software component that a database management system (DBMS) uses to create, read, update and delete (CRUD) data from a database. Most database management systems include their own application programming interface (API) that allows the user to interact with their underlying engine without going through the user interface of the DBMS. The term "database engine" is frequently used interchangeably with "database server" or "database management system". A "database instance" refers to the processes and memory structures of the running database engine. Storage engines Many of the modern DBMS support multiple storage engines within the same database. For example, MySQL supports InnoDB as well as MyISAM. Some storage engines are transactional. Additional engine types include: *Embedded database engines *In-memory database engines Design considerations Information in a database is stored as bits laid out as data structures in s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Storage Engine
A database engine (or storage engine) is the underlying software component that a database management system (DBMS) uses to create, read, update and delete (CRUD) data from a database. Most database management systems include their own application programming interface (API) that allows the user to interact with their underlying engine without going through the user interface of the DBMS. The term "database engine" is frequently used interchangeably with "database server" or "database management system". A "database instance" refers to the processes and memory structures of the running database engine. Storage engines Many of the modern DBMS support multiple storage engines within the same database. For example, MySQL supports InnoDB as well as MyISAM. Some storage engines are transactional. Additional engine types include: *Embedded database engines *In-memory database engines Design considerations Information in a database is stored as bits laid out as data structures in s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
MySQL
MySQL () is an open-source relational database management system (RDBMS). Its name is a combination of "My", the name of co-founder Michael Widenius's daughter My, and "SQL", the acronym for Structured Query Language. A relational database organizes data into one or more data tables in which data may be related to each other; these relations help structure the data. SQL is a language programmers use to create, modify and extract data from the relational database, as well as control user access to the database. In addition to relational databases and SQL, an RDBMS like MySQL works with an operating system to implement a relational database in a computer's storage system, manages users, allows for network access and facilitates testing database integrity and creation of backups. MySQL is free and open-source software under the terms of the GNU General Public License, and is also available under a variety of proprietary licenses. MySQL was owned and sponsored by the Swedish com ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Database Transaction
A database transaction symbolizes a unit of work, performed within a database management system (or similar system) against a database, that is treated in a coherent and reliable way independent of other transactions. A transaction generally represents any change in a database. Transactions in a database environment have two main purposes: # To provide reliable units of work that allow correct recovery from failures and keep a database consistent even in cases of system failure. For example: when execution prematurely and unexpectedly stops (completely or partially) in which case many operations upon a database remain uncompleted, with unclear status. # To provide isolation between programs accessing a database concurrently. If this isolation is not provided, the programs' outcomes are possibly erroneous. In a database management system, a transaction is a single unit of logic or work, sometimes made up of multiple operations. Any logical calculation done in a consistent mode in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
InnoDB
InnoDB is a database engine, storage engine for the database management system MySQL and MariaDB. Since the release of MySQL 5.5.5 in 2010, it replaced MyISAM as MySQL's default table type. It provides the standard ACID-compliant Database transaction, transaction features, along with foreign key support (Declarative Referential Integrity). It is included as standard in most binaries distributed by MySQL AB, the exception being some Original equipment manufacturer, OEM versions. Description InnoDB became a product of Oracle Corporation after its acquisition of the Finland-based company Innobase in October 2005. The software is dual licensed; it is distributed under the GNU General Public License, but can also be licensed to parties wishing to combine InnoDB in proprietary software. InnoDB supports: * Both SQL and X/Open XA, XA Database transaction, transactions * Tablespaces * Foreign keys * Full text search indexes, since MySQL 5.6 (February 2013) and MariaDB 10.0 * Spatial oper ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ISAM
ISAM (an acronym for indexed sequential access method) is a method for creating, maintaining, and manipulating computer files of data so that records can be retrieved sequentially or randomly by one or more keys. Indexes of key fields are maintained to achieve fast retrieval of required file records in Indexed files. IBM originally developed ISAM for mainframe computers, but implementations are available for most computer systems. The term ''ISAM'' is used for several related concepts: *The IBM ISAM product and the algorithm it employs. *A database system where an application developer directly uses an application programming interface to search indexes in order to locate records in data files. In contrast, a relational database uses a query optimizer which automatically selects indexes. *An indexing algorithm that allows both sequential and keyed access to data. Most databases use some variation of the B-tree for this purpose, although the original IBM ISAM and VSAM implementat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Drizzle (database Server)
Drizzle is a discontinued free software/open-source relational database management system (DBMS) that was forked from the now-defunct 6.0 development branch of the MySQL DBMS. Like MySQL, Drizzle had a client/server architecture and uses SQL as its primary command language. Old Drizzle files are distributed under version 2 and 3 of the GNU General Public License (GPL) with portions, including the protocol drivers and replication messaging under the BSD license. Early work on the fork was done mid-2008 by Brian Aker. Ongoing development was handled by a team of contributors that included staff members from Canonical Ltd., Google, Six Apart, Sun Microsystems, Rackspace, Data Differential, Blue Gecko, Intel, Percona, Hewlett-Packard, Red Hat, and others. Drizzle source code, along with instructions on compiling it, are available via the project's Launchpad website. In October 2010, Drizzle had 13,478 total contributions, 96 total contributors, and 37 active contributors. It w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
MariaDB
MariaDB is a community-developed, commercially supported fork of the MySQL relational database management system (RDBMS), intended to remain free and open-source software under the GNU General Public License. Development is led by some of the original developers of MySQL, who forked it due to concerns over its acquisition by Oracle Corporation in 2009. MariaDB is intended to maintain high compatibility with MySQL, with library binary parity and exact matching with MySQL APIs and commands, allowing it in many cases to function as drop-in replacement for MySQL. However, new features are diverging. It includes new storage engines like Aria, ColumnStore, and MyRocks. Its lead developer/CTO is Michael "Monty" Widenius, one of the founders of MySQL AB and the founder of Monty Program AB. On 16 January 2008, MySQL AB announced that it had agreed to be acquired by Sun Microsystems for approximately $1 billion. The acquisition completed on 26 February 2008. Sun was then bought the fo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Concurrency (computer Science)
In computer science, concurrency is the ability of different parts or units of a program, algorithm, or problem to be executed out-of-order or in partial order, without affecting the outcome. This allows for parallel execution of the concurrent units, which can significantly improve overall speed of the execution in multi-processor and multi-core systems. In more technical terms, concurrency refers to the decomposability of a program, algorithm, or problem into order-independent or partially-ordered components or units of computation. According to Rob Pike, concurrency is the composition of independently executing computations, and concurrency is not parallelism: concurrency is about dealing with lots of things at once but parallelism is about doing lots of things at once. Concurrency is about structure, parallelism is about execution, concurrency provides a way to structure a solution to solve a problem that may (but not necessarily) be parallelizable. A number of mathema ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
