A.8 MySQL 5.0 FAQ: Migration

A.8.1. Where can I find information on how to migrate from MySQL 4.1 to MySQL 5.0?
A.8.2. How has storage engine (table type) support changed in MySQL 5.0 from previous versions?

A.8.1.

Where can I find information on how to migrate from MySQL 4.1 to MySQL 5.0?

For detailed upgrade information, see Section 2.19.1, “Upgrading MySQL”. Do not skip a major version when upgrading, but rather complete the process in steps, upgrading from one major version to the next in each step. This may seem more complicated, but it will you save time and trouble—if you encounter problems during the upgrade, their origin will be easier to identify, either by you or—if you have a MySQL Enterprise subscription—by MySQL support.

A.8.2.

How has storage engine (table type) support changed in MySQL 5.0 from previous versions?

Storage engine support has changed as follows:

  • Support for ISAM tables was removed in MySQL 5.0 and you should now use the MyISAM storage engine in place of ISAM. To convert a table tblname from ISAM to MyISAM, simply issue a statement such as this one:

    ALTER TABLE tblname ENGINE=MYISAM;
  • Internal RAID for MyISAM tables was also removed in MySQL 5.0. This was formerly used to allow large tables in file systems that did not support file sizes greater than 2GB. All modern file systems allow for larger tables; in addition, there are now other solutions such as MERGE tables and views.

  • The VARCHAR column type now retains trailing spaces in all storage engines.

  • MEMORY tables (formerly known as HEAP tables) can also contain VARCHAR columns.


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