MySQL upgrade

upgrade=value

This option controls whether and how the server performs an automatic upgrade at startup. Automatic upgrade involves two steps:

• Step 1: Data dictionary upgrade.

  This step upgrades:

  • The data dictionary tables in the mysql schema. If the actual data dictionary version is lower than the current expected version, the server upgrades the data dictionary. If it cannot, or is prevented from doing so, the server cannot run.

  • The Performance Schema and INFORMATION_SCHEMA.

• Step 2: Server upgrade.

  This step comprises all other upgrade tasks. If the existing installation data has a lower MySQL version than the server expects, it must be upgraded:

  • The system tables in the mysql schema (the remaining non-data dictionary tables).

  • The sys schema.

  • User schemas.

For details about upgrade steps 1 and 2, see Section 2.10.3, “What the MySQL Upgrade Process Upgrades”.

These --upgrade option values are permitted:

• AUTO

  The server performs an automatic upgrade of anything it finds to be out of date (steps 1 and 2). This is the default action if --upgrade is not specified explicitly.

• NONE

  The server performs no automatic upgrade steps during the startup process (skips steps 1 and 2). Because this option value prevents a data dictionary upgrade, the server exits with an error if the data dictionary is found to be out of date:

  [ERROR] [MY-013381] [Server] Server shutting down because upgrade is
  required, yet prohibited by the command line option '--upgrade=NONE'.
  [ERROR] [MY-010334] [Server] Failed to initialize DD Storage Engine
  [ERROR] [MY-010020] [Server] Data Dictionary initialization failed.

• MINIMAL

  The server upgrades the data dictionary, the Performance Schema, and the INFORMATION_SCHEMA, if necessary (step 1). Note that following an upgrade with this option, Group Replication cannot be started, because system tables on which the replication internals depend are not updated, and reduced functionality might also be apparent in other areas.

• FORCE

  The server upgrades the data dictionary, the Performance Schema, and the INFORMATION_SCHEMA, if necessary (step 1). In addition, the server forces an upgrade of everything else (step 2). Expect server startup to take longer with this option because the server checks all objects in all schemas.

  FORCE is useful to force step 2 actions to be performed if the server thinks they are not necessary. For example, you may believe that a system table is missing or has become damaged and want to force a repair.

The following table summarizes the actions taken by the server for each option value.