content_image/787015.jpg content_image/787013.jpg
(These are not necessarily exact equivalents because a given --upgrade  option value may have additional effects.) 

<img src='content_image/787015.jpg'>

Additional notes about what occurs during upgrade step 2: 

•Step 2 installs the sys  schema if it is not installed, and upgrades it to the current version otherwise. An error occurs if a sys  schema exists but has no version  view, on the assumption that its absence indicates a user-created schema: 

A sys schema exists with no sys.version view. If you have a user created sys schema, this must be renamed for the upgrade to succeed. 

To upgrade in this case, remove or rename the existing sys  schema first. Then perform the upgrade procedure again. (It may be necessary to force step 2.) 

To prevent the sys  schema check: 

•As of MySQL 8.0.16: Start the server with the --upgrade=NONE  or --upgrade=MINIMAL  option. 

•Prior to MySQL 8.0.16: Invoke mysql_upgrade  with the --skip-sys-schema  option. 

•Step 2 processes all tables in all user schemas as necessary. Table checking might take a long time to complete. Each table is locked and therefore unavailable to other sessions while it is being processed. Check and repair operations can be time-consuming, particularly for large tables. Table checking uses the FOR UPGRADE  option of the CHECK TABLE  statement. For details about what this option entails, see Section 13.7.3.2, “CHECK TABLE Statement” . 

To prevent table checking: 

•As of MySQL 8.0.16: Start the server with the --upgrade=NONE  or --upgrade=MINIMAL  option. 

•Prior to MySQL 8.0.16: Invoke mysql_upgrade  with the --upgrade-system-tables  option. 

To force table checking: 

•As of MySQL 8.0.16: Start the server with the --upgrade=FORCE  option. 

•Prior to MySQL 8.0.16: Invoke mysql_upgrade  with the --force  option. 

•Step 2 saves the MySQL version number in a file named mysql_upgrade_info  in the data directory. 

To ignore the mysql_upgrade_info  file and perform the check regardless: 

•As of MySQL 8.0.16: Start the server with the --upgrade=FORCE  option. 

•Prior to MySQL 8.0.16: Invoke mysql_upgrade  with the --force  option. 

<img src='content_image/787013.jpg'>

## Note 

The mysql_upgrade_info  file is deprecated; expect it to be removed in a future version of MySQL. 

