MariaDB Enterprise Server InnoDB Undo Log

This page is part of MariaDB's Documentation.

The parent of this page is: InnoDB Architecture for MariaDB Enterprise Server

Topics on this page:

• Overview

• Feature Summary

• Basic Configuration

Overview

The InnoDB undo log is a transaction log used by InnoDB to keep track of multiple row versions for multi-version concurrency control (MVCC). When a row's value changes, InnoDB stores old versions of the row in the Undo Log.

When transactions are committed and the old row versions are no longer necessary, the InnoDB Purge Threads asynchronously delete old row versions from the Undo Log in the background.

When a transaction is rolled back, InnoDB uses the Undo Log to rollback the transaction's changes.