Multi versioning concurrency control (MVCC) is a database design theory that enables relational databases to support concurrency, or more simply multiple user access to common data in your database.
In my understanding of database theory, access to modify independent sections of unique data (e.g. UPDATE) under MVCC should fully support concurrency. I have however experienced a level of exclusive locking under Innodb.
I wanted to clearly document this situation so I could then seek the advice of the guru’s in InnoDB Internals such as Mark Callaghan, Percona and the Innodb development team for example. I’m happy …[Read more]