Installing MySQL - Learning MySQL - page 71

to other associated software—for example, the version of PHP that the application uses;
you must think carefully about the implications of an upgrade before diving in.
Before deciding to upgrade, read the release notes for the new version; in particular,
note any changes marked as an “incompatible change.” You can find a complete set of
release notes under the “MySQL Change History” section of the MySQL manual ( http:
//dev.mysql.com/doc/refman/5.1/en/news.html ) . For example, you may find that support
for something that you need is no longer available in the new version, or that you need
to carry out certain steps before you start the new server with your existing data. You
should also read the “Upgrading MySQL” section of the MySQL manual ( http://dev
.mysql.com/doc/refman/5.1/en/upgrade.html ) . Note that these links point to the latest
version of the manual (5.1) available at the time of writing.
In this topic, we don't describe how to change over from a non-MySQL database server,
such as Microsoft Access, Microsoft SQL Server, or Oracle. The MySQL Migration
Toolkit is a graphical tool that helps you through the process of moving your data over
to MySQL. You can download this program as as part of the MySQL GUI Tools Bundle
from the MySQL AB downloads page at http://dev.mysql.com/downloads .
Should I Upgrade to MySQL 5.1?
At the time of writing, MySQL 5.1 is in beta testing; this means that it's available for
easy use and testing, but that it's best to avoid using it for mission-critical production
sites. You can download and install MySQL 5.1 using the same procedures discussed
in this chapter for the Generally Available versions. Probably the most interesting new
features in MySQL 5.1 are its powerful text search capabilities, improved support for
XML data, and optimizations for applications where the server must handle very high
loads with very high reliability. It's likely that you won't need these features for a con-
siderable time after beginning to use MySQL, and you can complete all the examples
in this topic with any version of the MySQL server newer than 4.1.0 onwards.
How to Upgrade
We have seen in this chapter that different installation approaches place the MySQL
program and datafiles in different locations. For example, a MySQL AB RPM installs
the MySQL program files and the data directory under the /usr/local/mysql directory,
while a package provided by a Linux distribution typically places the MySQL program
files in the /usr/bin directory, and the datafiles in the /var/lib/mysql directory. Upgrading
a MySQL server installs new versions of the program files but will not affect your
datafiles.
The best way to ensure a trouble-free upgrade is to use the same approach as that used
to install the original server because the installation process can upgrade the existing
program files, and the new server will know where to find your datafiles. Alternatively,