Patches for MySQL 4.0 (historical document)

Introduction

These are patches for MySQL 4.0.26. They add many features that enhance the manageability and reliability of MySQL.

In a perfect world, each feature would be provided as a separate patch and all code would be as portable as MySQL. We are not there yet. These have been implemented and deployed on Linux. Also, some of these features only work with InnoDB, because we use InnoDB. They could be extended to support other storage engines.

The patch should be applied to MySQL 4.0.26 source code. That source is available from the download section for this project. The patch can be applied to the source as:

  tar xf mysql-4.0.26.tar.gz
  cd mysql-4.0.26
  patch --strip=1 --fuzz=1 < ../mysql-4.0.26-patches

Features

The patches include a few big features and many enhancements. The big features are:

• Semi Sync Replication Design - block commit on a master until at least one slave acknowledges receipt of all replication events.
• Mirrored Binlogs - maintain a copy of the master's binlog on a slave
• Transactional replication - make InnoDB and slave replication state consistent during crash recovery
• User table monitoring - monitor and report database activity per account and table
• Asynchronous IO in InnoDB - support multiple background IO threads for InnoDB
• Fast Master Promotion - promote a slave to a master without restart

Other enhancements include:

• Lossless FLOAT dump - support dump and restore of float/double without loss of precision
• Use 8X less memory for account and table privileges
• Use fastest compression rather than the default level for client/mysqld networking
• InnoDB Sampling - control the number of leaf blocks sampled for optimizer statistics
• New Show InnoDB Status - display more statistics in SHOW INNODB STATUS
• Reduced number of calls to fsync when the InnoDB background IO thread is active
• Changed InnoDB to recover when InnoDB and MySQL data dictionaries are inconsistent
• New SQL functions - functions for checksums and floating point to string conversion
• Backported START SLAVE UNTIL
• Sort float columns with the order: -INF < negative < 0 < positive < +INF < NaN
• Change long_query_time to be dynamic and log all queries that run for greater than or equal this number of seconds rather than greater than.
• Count connection attempts tha are denied because of max_connections and display the count as denied_connections
• More logging - log actions done on specified tables and SUPER users
• rpl_always_enter_innodb boosts the priority of the slave SQL thread (for replication) in InnoDB by making it ignore the InnoDB concurrency limits
• rpl_event_buffer_size sets the fixed size buffer that is allocated in the master for each connected slave. The buffer is used for replication events smaller than the buffer. This reduces memory allocation done to copy replication events from the master.
• Backported sync-binlog
• Added reserved_super_connections to reserve the final N connections for users with the SUPER privilege
• New Show Status - many new variables in SHOW STATUS