Compatibility Considerations for Downgrade and Backup

Because InnoDB 1.1 supports the “Barracuda” file format, with new on-disk data structures within both the database and log files, pay special attention to file format compatibility with respect to the following scenarios:

  • Downgrading from MySQL 5.5 to the MySQL 5.1 or earlier (without the InnoDB Plugin enabled), or otherwise using earlier versions of MySQL with database files created by MySQL 5.5 and higher.

  • Using mysqldump.

  • Using MySQL replication.

  • Using MySQL Enterprise Backup or InnoDB Hot Backup.

WARNING: Once you create any tables with the Barracuda file format, take care to avoid crashes and corruptions when using those files with an earlier version of InnoDB. It is strongly recommended that you use a “slow shutdown” (SET GLOBAL innodb_fast_shutdown=0) when stopping the MySQL server before downgrading to MySQL 5.1 or earlier. This ensures that the log files and other system information do not cause problems when using a prior version of InnoDB. See Section, “How to Downgrade”.

WARNING: If you dump a database containing compressed tables with mysqldump, the dump file may contain CREATE TABLE statements that attempt to create compressed tables, or those using ROW_FORMAT=DYNAMIC in the new database. Therefore, be sure the new database is running the InnoDB storage engine, with the proper settings for innodb_file_format and innodb_file_per_table, if you want to have the tables re-created as they exist in the original database. Typically, when the mysqldump file is loaded, MySQL and InnoDB ignore CREATE TABLE options they do not recognize, and the table(s) are created in a format used by the running server.

WARNING: If you use MySQL replication, ensure all slaves are configured with the InnoDB storage engine, with the same settings for innodb_file_format and innodb_file_per_table. If you do not do so, and you create tables that require the new “Barracuda” file format, replication errors may occur. If a slave MySQL server is running an older version of MySQL, it ignores the CREATE TABLE options to create a compressed table or one with ROW_FORMAT=DYNAMIC, and creates the table uncompressed, with ROW_FORMAT=COMPACT.

WARNING: Version 3.0 of InnoDB Hot Backup does not support the new “Barracuda” file format. Using InnoDB Hot Backup Version 3 to backup databases in this format causes unpredictable behavior. MySQL Enterprise Backup, the successor product to InnoDB Hot Backup, does support tables with the Barracuda file format. You can also back up such databases with mysqldump.

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