.. _version_2.3.9:

=============
Version 2.3.9
=============

Released on 2018/05/17.

If you are upgrading a cluster, you must be running CrateDB
:ref:`version_1.1.3` or higher before you upgrade to 2.3.9.

If you want to perform a `rolling upgrade`_, your current CrateDB
version number must be at least :ref:`version_2.3.0`. Any upgrade
from a version prior to this will require a `full restart upgrade`_.

.. WARNING::

   Before upgrading, you should `back up your data`_.

.. _rolling upgrade: http://crate.io/docs/crate/guide/best_practices/rolling_upgrade.html
.. _full restart upgrade: http://crate.io/docs/crate/guide/best_practices/full_restart_upgrade.html
.. _back up your data: https://crate.io/a/backing-up-and-restoring-crate/

Changelog
=========

Fixes
-----

- Fixed a stack overflow exception on upserts which could be caused by retries
  on version conflicts.

- Fixed a memory leak caused by using the ``hyperloglog_distinct`` function.
