redo log files and restart the MySQL 5.7 server on the existing data directory to address the errors. The redo log files ( ib_logfile* ) reside in the MySQL data directory by default. After the errors are fixed, perform a slow shutdown (by setting innodb_fast_shutdown=0 ) before attempting the upgrade again. 

## 2.11.13 Rebuilding or Repairing Tables or Indexes 

This section describes how to rebuild or repair tables or indexes, which may be necessitated by: 

•Changes to how MySQL handles data types or character sets. For example, an error in a collation might have been corrected, necessitating a table rebuild to update the indexes for character columns that use the collation. 

•Required table repairs or upgrades reported by CHECK TABLE , mysqlcheck , or mysql_upgrade . 

## Dump and Reload Method 

Methods for rebuilding a table include: 

•Dump and Reload Method 

•ALTER TABLE Method 

•REPAIR TABLE Method 

If you are rebuilding tables because a different version of MySQL cannot handle them after a binary (in-place) upgrade or downgrade, you must use the dump-and-reload method. Dump the tables before upgrading or downgrading using your original version of MySQL. Then reload the tables after  upgrading or downgrading. 

If you use the dump-and-reload method of rebuilding tables only for the purpose of rebuilding indexes, you can perform the dump either before or after upgrading or downgrading. Reloading still must be done afterward. 

If you need to rebuild an InnoDB  table because a CHECK TABLE  operation indicates that a table upgrade is required, use mysqldump  to create a dump file and mysql  to reload the file. If the CHECK TABLE operation indicates that there is a corruption or causes InnoDB  to fail, refer to Section 15.21.2, “Forcing InnoDB Recovery”  for information about using the innodb_force_recovery  option to restart InnoDB . To understand the type of problem that CHECK TABLE  may be encountering, refer to the InnoDB  notes in Section 13.7.3.2, “CHECK TABLE Statement” . 

To rebuild a table by dumping and reloading it, use mysqldump  to create a dump file and mysql  to reload the file: 

mysqldump db_name t1 > dump.sql mysql db_name  < dump.sql 

To rebuild all the tables in a single database, specify the database name without any following table name: 

mysqldump db_name  > dump.sql mysql db_name  < dump.sql 

To rebuild all tables in all databases, use the --all-databases  option: 

mysqldump --all-databases > dump.sql mysql < dump.sql 

