MySQL Redo Log: Unlocking the Mystery（mysql的redo日志）
MySQL Redo Log is an essential component of a database transaction system. It records all changes to the data and is used for recovery in case of system failure or crash. Redo logs are critical for ensuring the integrity and security of a database, as well as the performance of a high transactional system. Despite its importance, MySQL Redo Log is an often misunderstood concept and its true power can be unlocked when its internals are understood.
First off, the default location of redo log files is /var/lib/mysql. Second, a redo log is a write-ahead logging mechanism and records detailed information about each transaction in a binary format. Third, it is composed of several log files, called log files, each containing multiple logs much like a book. Fourth, redo log files are composed of two parts: the active part and the inactive part. Fifth, the active part contains the most recent transactions waiting to be committed, while the inactive part contains the transactions that have been fully committed.
The MySQL Redo Log also provides several features such as transaction isolation that guarantees transactions are not impacted by other transactions executing concurrently. Additionally, it is used to ensure data consistency so that if a transaction fails, it can be safely rolledback or undone. The data can also be replayed from the MySQL Redo log, which is also known as recovery to guarantee the stability and consistency of the system.
To ensure the integrity and security of the data, the log needs to be continuously written in a safe place, hence the precautionary measures for their placement, such as having multiple copies in different physical locations. This could be done with a few MySQL commands such as binlog_do_db, binlog_ignore_db, and log_bin. Additionally, log_bin_trust_function_creators and log_bin_trust_routine_creators help activate the feature to create an audit trail of all activity on the database.
In conclusion, MySQL Redo Log is critical to ensuring the integrity and security of a database while providing recovery options in case of system failure or crash. It is a highly complex mechanism and its true power is unlocked when its internals are understood. By utilizing a series of MySQL commands, proper implementations can be quickly and easily developed for maximum performance.
