5.2 The MySQL Data Directory

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:

  • The mysql directory corresponds to the mysql system database, which contains information required by the MySQL server as it runs. See Section 5.3, “The mysql System Database”.

  • The performance_schema directory corresponds to the Performance Schema, which provides information used to inspect the internal execution of the server at runtime. See Chapter 25, MySQL Performance Schema.

  • The sys directory corresponds to the sys schema, which provides a set of objects to help interpret Performance Schema information more easily. See Chapter 26, MySQL sys Schema.

  • The ndbinfo directory corresponds to the ndbinfo database that stores information specific to NDB Cluster (present only for installations built to include NDB Cluster). See Section 21.6.15, “ndbinfo: The NDB Cluster Information Database”.

  Other subdirectories correspond to databases created by users or applications.

  Note

  INFORMATION_SCHEMA is a standard database, but its implementation uses no corresponding database directory.

• Log files written by the server. See Section 5.4, “MySQL Server Logs”.

• InnoDB tablespace and log files. See Chapter 14, The InnoDB Storage Engine.

• Default/autogenerated SSL and RSA certificate and key files. See Section 6.3.3, “Creating SSL and RSA Certificates and Keys”.

• 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.