Hills and Headwinds

MySQL 8.0

First GA release : 8.0.11 (2018-04-19)

Some Changes from v5.7

• Data dictionary.  
  • MySQL now incorporates a transactional data dictionary that stores information about database objects.
• Security and account management.  
  
  • MySQL now supports roles, which are named collections of privileges. 
  • MySQL now maintains information about password history, enabling restrictions on reuse of previous passwords.
• InnoDB.  
  
  • All InnoDB temporary tables are now created in the shared temporary tablespace, ibtmp1. 
  • Now uses the MySQL data dictionary rather than its own storage engine-specific data dictionary.
  • mysql system tables and data dictionary tables are now created in a single InnoDB tablespace file named mysql.ibd in the MySQL data directory. 
• Optimizer
  
  • MySQL now supports invisible indexes. Invisible indexes make it possible to test the effect of removing an index on query performance, without making a destructive change.
• Internal temporary tables.  
  
  • The TempTable storage engine replaces the MEMORY storage engine as the default engine for in-memory internal temporary tables.

Some Features Removed in MySQL 8.0

• Using GRANT to create users
• Using GRANT to modify account properties other than privilege assignments.
• IDENTIFIED BY PASSWORD 'hash_string' syntax for CREATE USER and GRANT.
• The PASSWORD() function. Additionally, SET PASSWORD ... = PASSWORD('auth_string') syntax is no longer available. 
• The query cache has been removed.
• The data dictionary provides information about database objects, so the server no longer checks directory names in the data directory to find databases.
• The mysql_install_db program has been removed from distributions. Data directory initialization should be performed by invoking mysqld with the --initialize or --initialize-insecure option instead.
• System and status variable information is no longer maintained in the INFORMATION_SCHEMA. Use the corresponding Performance Schema tables instead.

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