Before upgrading from one release series to the next, please see the notes at section Upgrading MySQL.

Plans for some of the most requested features are summarized in the following table.

Feature MySQL Series Unions 4.0 Subqueries 4.1 R-trees 4.1 (for MyISAM tables) Stored procedures 5.0 Views 5.0 Cursors 5.0 Foreign keys 5.1 (implemented in 3.23 for InnoDB) Triggers 5.0 and 5.1 Full outer join 5.1 Constraints 5.1

MySQL Information Sources

MySQL Standards Compliance

This section describes how MySQL relates to the ANSI/ISO SQL standards. MySQL Server has many extensions to the SQL standard, and here you can find out what they are and how to use them. You can also find information about functionality missing from MySQL Server, and how to work around some differences.

The SQL standard has been evolving since 1986 and several versions exist. In this manual, ``SQL-92'' refers to the standard released in 1992, ``SQL:1999'' refers to the standard released in 1999, and ``SQL:2003'' refers to the current version of the standard. We use the phrase ``the SQL standard'' to mean the current version of the SQL Standard at any time.

Our goal is to not restrict MySQL Server usability for any usage without a very good reason for doing so. Even if we don't have the resources to perform development for every possible use, we are always willing to help and offer suggestions to people who are trying to use MySQL Server in new territories.

One of our main goals with the product is to continue to work toward compliance with the SQL standard, but without sacrificing speed or reliability. We are not afraid to add extensions to SQL or support for non-SQL features if this greatly increases the usability of MySQL Server for a large segment of our user base. The HANDLER interface in MySQL Server 4.0 is an example of this strategy. See section HANDLER Syntax.

We continue to support transactional and non-transactional databases to satisfy both mission-critical 24/7 usage and heavy Web or logging usage.

MySQL Server was originally designed to work with medium size databases (10-100 million rows, or about 100MB per table) on small computer systems. Today MySQL Server handles terabyte-size databases, but the code can also be compiled in a reduced version suitable for hand-held and embedded devices. The compact design of the MySQL server makes development in both directions possible without any conflicts in the source tree.

Currently, we are not targeting realtime support, although MySQL replication capabilities offer significant functionality.

Database cluster support exists through third-party clustering solutions as well as the integration of our acquired NDB Cluster technology, available from version 4.1.2. See section MySQL Cluster.

We are also looking at providing XML support in the database server.

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