MySQL 5.5 Release Notes

MySQL 5.5 Release Notes


This document contains release notes for the changes in each release of MySQL 5.5, up through MySQL 5.5.62. For information about changes in a different MySQL series, see the release notes for that series.

For additional MySQL 5.5 documentation, see the MySQL 5.5 Reference Manual, which includes an overview of features added in MySQL 5.5 (What Is New in MySQL 5.5), and discussion of upgrade issues that you may encounter for upgrades from MySQL 5.1 to MySQL 5.5 (Changes in MySQL 5.5).

Updates to these notes occur as new product features are added, so that everybody can follow the development process. If a recent version is listed here that you cannot find on the download page (, the version has not yet been released.

The documentation included in source and binary distributions may not be fully up to date with respect to release note entries because integration of the documentation occurs at release build time. For the most up-to-date release notes, please refer to the online documentation instead.

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.

MySQL development now uses a milestone model. The move to this model provides for more frequent milestone releases, in which each milestone introduces a small subset of thoroughly tested features. Following the releases for one milestone, development proceeds with another small number of releases that focuses on the next set of features. From one milestone to the next, feature interfaces may change or features may even be removed, based on feedback provided by community members who try these earily releases. Features within milestone releases may be considered to be of pre-production quality.

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.

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Document generated on: 2020-02-03 (revision: 19716)

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