MySQL is a relational database management system developed by the Swedish MySQL AB company and is currently a product of Oracle. MySQL is one of the most popular relational database management systems. In terms of WEB applications, MySQL is the best RDBMS (Relational Database Management System) application software.
Comparison of MySQL versions:
mysql5.7 : Released in 2015, the query performance of mysql5.7 has been greatly improved. Compared with MySQL 5.6, it is doubled and the time to establish a database connection is reduced.
mysql5.6 : Released in February 2013, mysql5.6 version in which InnoDB can limit the problem of excessive memory usage when a large number of tables are opened, improves InnoDB performance. InnoDB deadlock information such as large memory optimization can be recorded to the error log to facilitate analysis. InnoDB provides full-text indexing capabilities.
mysql5.5: The default storage engine of mysql5.5 version was released in December 2010 and was changed to InnoDB multiple rollback segments (Multiple Rollback Segments). The previous innodb version can handle a maximum of 1023 concurrent processing operations. Now mysql5.5 can handle up to 128K concurrent transactions and improve metadata locking in transaction processing. For example, if a statement in a transaction needs to lock a table, the table will be released at the end of the transaction, instead of releasing the table at the end of the statement as before. The INFORMATION_SCHEMA[ˈski:mə]] table has been added. The new table provides specific information related to InnoDB compression and transaction locking.
mysql5.1 : The version of MySQL 5.1 released in 20o8 is basically a MyISAM with added crash recovery function. It uses table-level locks, but can achieve no conflict in reading and writing, that is, any type of Read operations can be performed at the same time as the update operation, but multiple write operations cannot be performed concurrently.
mysql-5.0 : Before mysql-5.0 version, the default table size supported by myisam was 4G. From mysql-5.0 onwards, myisam supports 256T form data by default. myisam only caches index data. Version 5.0 in 2005 added stored procedures, server-side cursors, triggers, query optimization, and distributed transaction functions.
mysql-4.1 : The 4.0 Beta version released in 2002. At this point, MySQL has finally transformed into a mature relational database system. In 2002, the mysql4.1 version added support for subqueries, added UTF-8 to the character set, added ROLLUP to the GROUP BY statement, and adopted a better encryption algorithm for the MySQL.user table. Tables that support each innodb engine are placed in a separate table space. Innodb obtains high concurrency by using MVCC (Multiple Version Concurrency Control), and implements the four isolation levels of the SQL standard. It also uses a strategy called next-key locking to avoid phantom reading (phantom). In addition, the innodb engine also provides high-performance technologies such as insert buffer, double write, adaptive hash index, and read ahead.
Specifically, which MySQL version is best needs to be determined based on the actual application. It is recommended that you refer to the following MySQL database GA version selection process, as described below:
1 . Analyze whether the basic functions and features of MySQL need to be used in the business of this enterprise. The key research directions of features are: MySQL replication, partition table, Plugin-innodb, etc.
2. The first GA version of the MySQL database product line must be launched for at least 10 months before it is considered to be used in the production environment.
3. The latest GA version of the MySQL database product line is generally not the first choice. You can consider a GA version database that is 3 to 4 versions later than the latest version.
4. Carefully read the information about the GA version of the target database. If a large number of BUGs have been modified based on the previous version, select this GA version carefully.
5. Carefully read the information of the first version after the GA version of the target database. If the amount of modified BUG information is very large, please directly abandon the target version and advance one version number as the target version.
6. Select according to the method described in the fourth and fifth steps until a version after the selected version has few BUG modifications, very few serious BUGs, and is not the latest GA version
7. Read in detail the BUG repair information of the 2 to 3 versions after the selected database GA version, mainly related to the target GA version, and find ways to reproduce it and find ways to avoid it.
8. For the GA version selected through the above seven steps, functional testing and performance testing must be carried out in conjunction with the functions that may be needed by enterprise business.
9. The selected GA version of the database is used as an internal development and testing database environment and usually requires a trial run of about 3-6 months.
10. Enterprises’ non-core businesses can consider adopting the new GA version.
11. After the above 10 processes, if there are no important functional bugs or performance bottlenecks, you can start to consider the back-end database as all business data services.
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