Partitioning.  This capability enables distributing portions of individual tables across a filesystem, according to rules which can be set when the table is created. In effect, different portions of a table are stored as separate tables in different locations, but from the user point of view, the partitioned table is still a single table. Syntactically, this implements a number of new extensions to the CREATE TABLE, ALTER TABLE, and EXPLAIN ... SELECT statements. As of MySQL 5.1.6, queries against partitioned tables can take advantage of partition pruning. In some cases, this can result in query execution that is an order of magnitude faster than the same query against a non-partitioned version of the same table. See Chapter 16, Partitioning, for further information on this functionality. (Author: Mikael Ronström)

Row-based replication.  Replication capabilities in MySQL originally were based on propagation of SQL statements from master to slave. This is called statement-based replication. As of MySQL 5.1.5, another basis for replication is available. This is called row-based replication. Instead of sending SQL statements to the slave, the master writes events to its binary log that indicate how individual table rows are effected. As of MySQL 5.1.8, a third option is available: mixed. This will use statement-based replication by default, and only switch to row-based replication in particular cases. See Section 14.1.2, “Replication Formats”. (Authors: Lars Thalmann, Guilhem Bichot, Mats Kindahl)

Plugin API.  MySQL 5.1 adds support for a very flexible plugin API that enables loading and unloading of various components at runtime, without restarting the server. Although the work on this is not finished yet, plugin full-text parsers are a first step in this direction. This allows users to implement their own input filter on the indexed text, enabling full-text search capability on arbitrary data such as PDF files or other document formats. A pre-parser full-text plugin performs the actual parsing and extraction of the text and hands it over to the built-in MySQL full-text search. See Section 27.2, “The MySQL Plugin Interface”. (Author: Sergey Vojtovich)

Event scheduler.  MySQL Events are tasks that run according to a schedule. When you create an event, you are creating a named database object containing one or more SQL statements to be executed at one or more regular intervals, beginning and ending at a specific date and time. Conceptually, this is similar to the idea of the Unix crontab (also known as a “ cron job”) or the Windows Task Scheduler. See Chapter 20, Event Scheduler. (Author: Andrey Hristov)

Server log tables.  Before MySQL 5.1, the server writes general query log and slow query log entries to log files. As of MySQL 5.1, the server's logging capabilities for these logs are more flexible. Log entries can be written to log files (as before) or to the general_log and slow_log tables in the mysql database. If logging is enabled, either or both destinations can be selected. The --log-output option controls the destination or destinations of log output. See Section 5.2.1, “Selecting General Query and Slow Query Log Output Destinations”. (Author: Petr Chardin)

Upgrade program.  The mysql_upgrade program (available as of MySQL 5.1.7) checks all existing tables for incompatibilities with the current version of MySQL Server and repairs them if necessary. This program should be run for each MySQL upgrade. See Section 4.4.7, “ mysql_upgrade — Check Tables for MySQL Upgrade”. (Authors: Alexey Botchkov, Mikael Widenius)

MySQL Cluster replication.  Replication between MySQL Clusters is now supported. It is now also possible to replicate between a MySQL Cluster and a non-cluster database. See Section 15.10, “MySQL Cluster Replication”.

MySQL Cluster disk data storage.  In MySQL versions previous to 5.1.6, the NDBCluster storage engine was strictly in-memory; beginning with MySQL 5.1.6, it is possible to store Cluster data (but not indexes) on disk. This allows MySQL Cluster to scale upward with fewer hardware (RAM) requirements than previously. In addition, the Disk Data implementation includes a new “ no-steal” restoration algorithm for fast node restarts when storing very large amounts of data (terabyte range). See Section 15.11, “MySQL Cluster Disk Data Tables”.

Improved backups for MySQL Cluster.  A fault arising in a single data node during a Cluster backup no longer causes the entire backup to be aborted, as occurred in previous versions of MySQL Cluster.

Backup of tablespaces.  The mysqldump utility now supports an option for dumping tablespaces. Use -Y or --all-tablespaces to enable this functionality.

Improvements to INFORMATION_SCHEMA.  MySQL 5.1 provides much more information in its metadata database thasn was available in MySQL 5.0. New tables in the INFORMATION_SCHEMA database include FILES, EVENTS, PARTITIONS, PROCESSLIST, ENGINES, and PLUGINS.

XML functions with XPath support.  ExtractValue() returns the content of a fragment of XML matching a given XPath expression. UpdateXML() replaces the element selected from a fragment of XML by an XPath expression supplied by the user with a second XML fragment (also user-supplied), and returns the modified XML. See Section 10.10, “XML Functions”. (Author: Alexander Barkov)

Load emulator.  The mysqlslap program is designed to emulate client load for a MySQL server and report the timing of each stage. It works as if multiple clients were accessing the server. See Section 4.5.7, “ mysqlslap — Load Emulation Client”.