Databases Reference
In-Depth Information
Version 5.0 (2006)
A number of “enterprise” features appeared in this release: views, triggers, stored
procedures, and stored functions. The ISAM engine was removed completely, but
new storage engines such as Federated were introduced.
Version 5.1 (2008)
This release was the first under Sun Microsystems's ownership after its acquisition
of MySQL AB, and was over five years in the making. Version 5.1 introduced par-
titioning, row-based replication, and a variety of plugin APIs, including the
pluggable storage engine API. The BerkeleyDB storage engine—MySQL's first
transactional storage engine—was removed and some others, such as Federated,
were deprecated. Also, Oracle, now the owner of Innobase Oy,
5
released the
InnoDB plugin storage engine.
Version 5.5 (2010)
MySQL 5.5 was the first release following Oracle's acquisition of Sun (and there-
fore MySQL). It focused on improvements to performance, scalability, replication,
partitioning, and support for Microsoft Windows, but included many other im-
provements as well. InnoDB became the default storage engine, and many legacy
features and deprecated options and behaviors were scrubbed. The
PERFORMANCE
_SCHEMA
database was added, along with a first batch of enhanced instrumentation.
New plugin APIs for replication, authentication, and auditing were added. A plugin
for semisynchronous replication was available, and Oracle released commercial
plugins for authentication and thread pooling in 2011. There were also major ar-
chitectural changes to InnoDB, such as a partitioned buffer pool.
Version 5.6 (Unreleased)
MySQL 5.6 will have a raft of new features, including the first major improvements
to the query optimizer in many years, more plugin APIs (e.g., one for full-text
search), replication improvements, and greatly expanded instrumentation in the
PERFORMANCE_SCHEMA
database. The InnoDB team is also hard at work, with a huge
variety of changes and improvements having been released in development mile-
stones and lab previews. Whereas MySQL 5.5 seemed to be about firming up and
fixing the fundamentals, with a limited number of new introductions, MySQL 5.6
appears to be focused on advancing server development and performance, using
5.5's success as a springboard.
Version 6.0 (Canceled)
Version 6.0 is confusing because of the overlapping chronology. It was announced
during the 5.1 development years. There were rumors or promises of many new
features, such as online backups and server-level foreign keys for all storage en-
gines, subquery improvements, and thread pooling. This release was canceled, and
Sun resumed development with version 5.4, which was eventually released as
5. Oracle also now owns BerkeleyDB.
