( Upgrade

Info Catalog ( Post-installation ( Installing ( Downgrading
 2.10 Upgrading MySQL
 As a general rule, we recommend that when upgrading from one release
 series to another, you should go to the next series rather than
 skipping a series. For example, if you currently are running MySQL 3.23
 and wish to upgrade to a newer series, upgrade to MySQL 4.0 rather than
 to 4.1 or 5.0.
 The following items form a checklist of things you should do whenever
 you perform an upgrade:
    * Read the upgrading section for the release series to which you are
      upgrading.  Read the change notes as well.  These provide
      information about new features you can use.  For example, before
      upgrading from MySQL 4.1 to 5.0, read the 5.0 upgrading section
      ( Upgrading-from-4.1) and read the 5.0 change notes (
    * Before you do an upgrade, back up your databases.
    * If you are running MySQL Server on Windows, see  Windows
    * An upgrade may involve changes to the grant tables that are stored
      in the `mysql' database. Occasionally new columns or tables are
      added to support new features.  To take advantage of these
      features, be sure that your grant tables are up to date.  The
      upgrade procedure is described in  Upgrading-grant-tables.
    * If you are using replication, see  Replication Upgrade for
      information on upgrading your replication setup.
    * If you install a MySQL-Max distribution that includes a server
      named `mysqld-max', then upgrade later to a non-Max version of
      MySQL, `mysqld_safe' will still attempt to run the old `mysqld-max'
      server.  If you perform such an upgrade, you should manually
      remove the old `mysqld-max' server to ensure that `mysqld_safe'
      runs the new `mysqld' server.
 You can always move the MySQL format files and data files between
 different versions on the same architecture as long as you stay within
 versions for the same release series of MySQL. The current production
 release series is 4.1. If you change the character set when running
 MySQL, you must run `myisamchk -r -q --set-character-set=CHARSET' on
 all `MyISAM' tables.  Otherwise, your indexes may not be ordered
 correctly, because changing the character set may also change the sort
 Normally you can upgrade MySQL to a newer MySQL version without having
 to do any changes to your tables.  Please confirm if the upgrade notes
 to the particular version you are upgrading to tells you anything about
 this.  If there would be any incompatibilities you can use `mysqldump'
 to dump your tables before upgrading. After upgrading, reload the dump
 file using `mysql' or `mysqlimport' to re-create your tables.
 If you are cautious about using new versions, you can always rename
 your old `mysqld' before installing a newer one. For example, if you
 are using MySQL 4.0.18 and want to upgrade to 4.1.1, rename your
 current server from `mysqld' to `mysqld-4.0.18'.  If your new `mysqld'
 then does something unexpected, you can simply shut it down and restart
 with your old `mysqld'.
 If, after an upgrade, you experience problems with recompiled client
 programs, such as `Commands out of sync' or unexpected core dumps, you
 probably have used old header or library files when compiling your
 programs.  In this case, you should check the date for your `mysql.h'
 file and `libmysqlclient.a' library to verify that they are from the new
 MySQL distribution.  If not, recompile your programs with the new
 headers and libraries.
 If problems occur, such as that the new `mysqld' server doesn't want to
 start or that you can't connect without a password, verify that you
 don't have some old `my.cnf' file from your previous installation.  You
 can check this with the `--print-defaults' option (for example, `mysqld
 --print-defaults').  If this displays anything other than the program
 name, you have an active `my.cnf' file that affects server or client
 It is a good idea to rebuild and reinstall the Perl `DBD::mysql' module
 whenever you install a new release of MySQL. The same applies to other
 MySQL interfaces as well, such as the PHP `mysql' extension and the
 Python `MySQLdb' module.


* Upgrading-from-4.1          Upgrading from Version 4.1 to 5.0
* Upgrading-from-4.0          Upgrading from Version 4.0 to 4.1
* Upgrading-from-3.23         Upgrading from Version 3.23 to 4.0
* Upgrading-from-3.22         Upgrading from Version 3.22 to 3.23
* Upgrading-from-3.21         Upgrading from Version 3.21 to 3.22
* Upgrading-from-3.20         Upgrading from Version 3.20 to 3.21
* Upgrading-grant-tables      Upgrading the Grant Tables
* Upgrading-to-arch           Copying MySQL Databases to Another Machine
Info Catalog ( Post-installation ( Installing ( Downgrading
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