3. Isolation

• Transaction is only supported by the InnoDB storage engine
• Isolation is to solve these problems:
  • Dirty read
  • Non-repeatable read
  • phantom read
• Isolation levels:
  • Read uncommitted
  • Read committed
  • Repeatable read
  • Serializable
• Implementation of isolation:
  • Use MVCC (multi-version concurrency control)
  • Achived with the undo tablespaces
  • Undo tablespaces could only be deleted when there is no older read-view
  • See https://dev.mysql.com/doc/refman/8.0/en/innodb-multi-versioning.html