.. _version_4.6.6:

=============
Version 4.6.6
=============

Released on 2021-12-13.

.. NOTE::

    If you are upgrading a cluster, you must be running CrateDB 4.0.2 or higher
    before you upgrade to 4.6.6.

    We recommend that you upgrade to the latest 4.3 release before moving to
    4.6.6.

    A rolling upgrade from 4.5.x to 4.6.6 is supported.

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

.. _back up your data: https://crate.io/docs/crate/reference/en/latest/admin/snapshots.html



.. rubric:: Table of Contents

.. contents::
   :local:


See the :ref:`version_4.6.0` release notes for a full list of changes in the
4.6 series.

Fixes
=====

- Updated ``log4j`` to 2.15.0 to fix a security vulnerability. See `Log4Shell
  <https://en.wikipedia.org/wiki/Log4Shell>`_ for details.

- Fixed an issue that could result in an error if a client sent multiple
  statements in a single string using the PostgreSQL simple protocol mode.

- Improved the detection of the cgroup version to support kernels where the
  `cpu.stat` and `memory.stat` files weren't available at the cgroup root
  level.

- Fixed an issue that could cause a deadlock, leading to an unavailable cluster
  if using blob tables and uploading multiple files in parallel.

- Fixed an issue that was triggered by adding a column to a table with existing
  generated columns with `ALTER TABLE`. It caused the `generated columns` to
  become non-generated such that it could no longer generate the values.
