Information managed by the MySQL server is stored under a directory known as the data directory. The following list briefly describes the items typically found in the data directory, with cross references for additional information:
Data directory subdirectories. Each subdirectory of the data directory is a database directory and corresponds to a database managed by the server. All MySQL installations have certain standard databases:
mysqldirectory corresponds to the
mysqlsystem database, which contains information required by the MySQL server as it runs. See Section 5.3, “The mysql System Database”.
performance_schemadirectory corresponds to the Performance Schema, which provides information used to inspect the internal execution of the server at runtime. See Chapter 22, MySQL Performance Schema.
ndbinfodirectory corresponds to the
ndbinfodatabase that stores information specific to NDB Cluster (present only for installations built to include NDB Cluster). See Section 18.6.14, “ndbinfo: The NDB Cluster Information Database”.
Other subdirectories correspond to databases created by users or applications.Note
INFORMATION_SCHEMAis a standard database, but its implementation uses no corresponding database directory.
Log files written by the server. See Section 5.4, “MySQL Server Logs”.
InnoDBtablespace and log files. See Chapter 14, The InnoDB Storage Engine.
The server process ID file (while the server is running).
Some items in the preceding list can be relocated elsewhere by
reconfiguring the server. In addition, the
--datadir option enables the
location of the data directory itself to be changed. For a given
MySQL installation, check the server configuration to determine
whether items have been moved.