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MySQL Server Version Reference :: 5 Key changes in MySQL releases :: 5.4 Key changes in MySQL 5.5 releases :: 5.4.4 Changes in MySQL 5.5.0 (07 December 2009 Milestone 2)
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5.4.4. Changes in MySQL 5.5.0 (07 December 2009 Milestone 2)

Previously, MySQL development proceeded by including a large set of features and moving them over many versions within a release series through several stages of maturity (Alpha, Beta, and so forth). This development model had a disadvantage in that problems with only part of the code could hinder timely release of the whole. As you might have found when testing MySQL Server 6.0, alpha quality code could jeopardize the stability of the entire release. (One consequence of this was that MySQL Server 6.0 has been withdrawn for now.)

MySQL development now uses a milestone model. The move to this model provides for more frequent milestone releases, with each milestone proceeding through a small number of releases having a focus on a specific subset of thoroughly tested features. Following the releases for one milestone, development proceeds with the next milestone; that is, another small number of releases that focuses on the next small set of features, also thoroughly tested.

MySQL 5.5.0-m2 is the first release for Milestone 2. The new features of this milestone may be considered to be initially of beta quality. For subsequent Milestone 2 releases, we plan to use increasing version numbers (5.5.1 and higher) while continuing to employ the “-m2” suffix. For Milestone 3, we plan to change the suffix to “-m3”. Version designators with “-alpha” or “-beta” suffixes are no used.

You may notice that the MySQL 5.5.0 release is designated as Milestone 2 rather than Milestone 1. This is because MySQL 5.4 was actually designated as Milestone 1, although we had not yet begun referring to milestone numbers as part of version numbers at the time.

Functionality added or changed:

  • Incompatible Change: MySQL Server now includes a plugin services interface that complements the plugin API. The services interface enables server functionality to be exposed as a “service” that plugins can access through a function-call interface. The libmysqlservices library provides access to the available services and dynamic plugins now must be linked against this library (use the -lmysqlservices flag). For an example showing what Makefile.am should look like, see MySQL Services for Plugins. (Bug#48461)

  • Incompatible Change: Several changes have been made regarding the language and character set of error messages:

    • The --language option for specifying the directory for the error message file is now deprecated. The new --lc-messages-dir and --lc-messages options should be used instead, and --language is handled as an alias for --lc-messages-dir.

    • The language system variable has been removed and replaced with the new lc_messages_dir and lc_messages system variables. lc_messages_dir has only a global value and is read only. lc_messages has global and session values and can be modified at runtime, so the error message language can be changed while the server is running, and individual clients each can have a different error message language by changing their session lc_messages value to a different locale name.

    • Error messages previously were constructed in a mix of character sets. This issue is resolved by constructing error messages internally within the server using UTF-8 and returning them to the client in the character set specified by the character_set_results system variable. The content of error messages therefore may in some cases differ from the messags returned previously.

    For more information, see Setting the Error Message Language, and Character Set for Error Messages.

    See also Bug#46218, Bug#46236.

Bugs fixed:

  • Important Change: Security Fix: It was possible to circumvent privileges through the creation of MyISAM tables employing the DATA DIRECTORY and INDEX DIRECTORY options to overwrite existing table files in the MySQL data directory. Use of the MySQL data directory in DATA DIRECTORY and INDEX DIRECTORY is now disallowed. This is now also true of these options when used with partitioned tables and individual partitions of such tables. (Bug#32167, CVE-2008-2079)

    See also Bug#39277.

  • Security Fix: MySQL clients linked against OpenSSL can be tricked not to check server certificates. (Bug#47320, CVE-2009-4028)

  • Security Fix: The server crashed if an account without the proper privileges attempted to create a stored procedure. (Bug#44658)

  • Incompatible Change: For system variables that take values of ON or OFF, OF was accepted as a legal variable. Now system variables that take “enumeration” values must be assigned the full value. This affects some other variables that previously could be assigned using unambiguous prefixes of allowable values, such as tx_isolation. (Bug#34828)

  • Incompatible Change: In binary installations of MySQL, the supplied binary-configure script would start and configure MySQL, even when command help was requested with the --help command-line option. The --help, if provided, will no longer start and install the server. (Bug#30954)

  • Incompatible Change: Access privileges for several statements are more accurately checked:

    • CHECK TABLE requires some privilege for the table.

    • CHECKSUM TABLE requires SELECT for the table.

    • CREATE TABLE ... LIKE requires SELECT for the source table and CREATE for the destination table.

    • SHOW COLUMNS displays information only for those columns you have some privilege for.

    • SHOW CREATE TABLE requires some privilege for the table (previously required SELECT).

    • SHOW CREATE VIEW requires SHOW VIEW and SELECT for the view.

    • SHOW INDEX requires some privilege for any column.

    • SHOW OPEN TABLES displays only tables for which you have some privilege on any table column.

    (Bug#27145)