Learning MySQL

Upgrading an Existing MySQL Server

If you’ve got a MySQL server that’s running well and without problems, you may wonder whether it’s necessary to upgrade it to the latest version. There are three main reasons to upgrade:

Fixes for bugs

No complex software such as MySQL can be free of bugs; over time, people discover unexpected behavior, or possible data corruption. As these problems come to light, they are fixed for the latest version. MySQL bugs are reported and analyzed at the http://bugs.mysql.com web site. You can use this web site to view the bug reports for your MySQL version and determine whether any are likely to affect your operations.

Fixes for security vulnerabilities

Security vulnerabilities are an especially dangerous class of bug; by exploiting a vulnerability, an attacker could gain unauthorized access to data, or render your system unusable (cause a denial of service). If your server is connected to a network or otherwise accessible to people other than yourself, you need to take security issues very seriously.

Improved features

As software matures, new features are added to make some tasks easier or to improve efficiency. For example, MySQL 5.0 introduced support for views (virtual tables), stored procedures (predefined queries that clients can call), cursors (pointers to the result of database operations), and triggers (predefined operations that are carried out automatically before or after a row is inserted, deleted, or updated). Similarly, subqueries (nested SELECT ...