Because the InnoDB Plugin introduces a new file format, with new on-disk data structures within both the database and log files, there are important restrictions on the use of the plugin in typical user environments. Specifically, you should pay special attention to the information presented here about file format compatibility with respect to the following scenarios:
Downgrading from the InnoDB Plugin to the built-in InnoDB, or otherwise using different versions of InnoDB with database files created by the InnoDB Plugin
Using MySQL replication.
Using InnoDB Hot Backup.
WARNING: Once you use the
InnoDB Plugin on a set of database files, take care to avoid
crashes and corruptions when using those files with an earlier
version of InnoDB, as might happen by opening the database with
MySQL when the plugin is not installed. It is
strongly recommended that you
use a “slow shutdown” (
innodb_fast_shutdown=0) when stopping the MySQL server
when the InnoDB Plugin is enabled. This will ensure log files
and other system information written by the plugin will not cause
problems when using a prior version of InnoDB. See
Section 11.3, “How to Downgrade”.
Because of these considerations, and although it may be useful in certain circumstances to use the plugin in a temporary way as just described, many users will find it preferable to test their application with the plugin and use it on an on-going basis, without reverting back to the standard, built-in InnoDB.
WARNING: If you dump a database
containing compressed tables with
the dump file may contain
CREATE TABLE commands that attempt to
create compressed tables, or those using
the new database. Therefore, you should be sure the new database
is running the InnoDB Plugin, with the proper settings for
innodb_file_per_table, if you want to
have the tables re-created as they exist in the original database.
Typically, however, when the
mysqldump file is
loaded, MySQL and InnoDB will ignore
CREATE TABLE options
they do not recognize, and the table(s) will be created in a
format used by the running server.
WARNING: If you use MySQL
replication, you should be careful to ensure all slaves are
configured with the InnoDB Plugin, with the same settings for
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 the built-in InnoDB, it will ignore the
options to create a compressed table or one with
ROW_FORMAT=DYNAMIC, and create the table uncompressed, with
WARNING: The current version of
InnoDB Hot Backup does not support the new “Barracuda” file format.
Using InnoDB Hot Backup Version 3 to backup databases in this format will
cause unpredictable behavior. A future version of InnoDB Hot Backup will
support databases used with the InnoDB Plugin. As an
alternative, you may back up such databases with