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Definition of ibfile set

To avoid confusion, for the purposes of this discussion we define the term “ib-file set” to mean the set

of operating system files that InnoDB manages as a unit. The ib-file set includes the following files:

•    The system tablespace (one or morę ibdata files) that contain internal system information

(including internal catalogs and undo information) and may include user data and indexes.

•    Zero or morę single-table tablespaces (also called “file per table" files, named *. ibd files).

•    InnoDB log files; usually two, ib_logfileO and ib_logfilel. Used for crash recovery and in

backups.

An “ib-file set" does not include the corresponding . f rm files that contain metadata about InnoDB

tables. The . f rm files are created and managed by MySQL, and can sometimes get out of sync with the internal metadata in InnoDB.

Multiple tables, even from morę than one database, can be stored in a single “ib-file set”. (In MySQL, a

“database” is a logical collection of tables, what other systems refer to as a “schema” or "catalog".)