WL#6392: Upgrade to Transactional Data Dictionary

Affects: Server-8.0   —   Status: Complete

Introduction

With the implementation of the new data dictionary, the metadata will be stored
in the InnoDB tables. For the users to upgrade from the older MySQL
version(5.7), a provision needs to be made which will help in

- migrating the metadata from mysql-5.7 to DD tables in 8.0.
- Remove .frm, .par, .TRG, .TRN, other files which are currently used for 
  metadata storage.

Definitions

DD             : New Data Dictionary.
dd::<tables>   : Data dictionary tables like dd::tables, dd::columns.

"upgrade" and "migrate" have been used alternately in the worklog page.

Worklog goals and scope

- This worklog will deal with the in place (live) server version upgrade from 
  mysql-5.7, which stores metadata in files (.frm, .TRG, ...) and some in MyISAM
  tables (mysql.proc, mysql.events) to mysql-8.0, which implements New DD.
- Major or minor version upgrade of DD is not in scope of this worklog.
- Downgrade from mysql-8.0 to a lower version which do not support DD is not in
  the scope of this worklog. See detailed discussion below.
- Migration of InnoDB internal dictionary to DD is not in scope of this worklog.