MariaDB MaxScale 2.3.1 Release Notes -- 2018-11-20

MariaDB MaxScale 2.3.1 Release Notes -- 2018-11-20

Release 2.3.1 is a Beta release.

This document describes the changes in release 2.3.1, when compared to the previous release in the same series.

For any problems you encounter, please consider submitting a bug report on our Jira.

Changed Features

Unknown global parameters

Unknown global parameters or parameters with invalid values are now treated as errors. If MaxScale refuses to start after upgrading to 2.3.1, check whether it is due to an unknown global parameter.



The response will, if the feature has been enabled with the retain_last_statements parameter, either globally or specifically for a service, contain information about the last queries executed by a session.

Binlog Router

Secondary masters can now be specified also when file + position based replication is used. Earlier it was possible only in conjunction with GTID based replication.

mmmon and ndbclustermon

Both of these modules have been deprecated and will be removed in a future release. The functionality in mmmon has been largely obsoleted by the advancements in mariadbmon. The ndbclustermon is largely obsolete due to the fact that there are virtually no users who use it.

Deprecated features

The following configuration file options have been deprecated and will be removed in 2.4.

Global section

  • non_blocking_polls, ignored.
  • poll_sleep, ignored.
  • thread_stack_size, ignored.

Services and Monitors

  • passwd, replaced with password.


MaxAdmin has been deprecated in favor of the REST API and MaxCtrl. It will be removed in a later release.

In addition to this the commands set pollsleep and set nbpolls have been deprecated and will be removed already in 2.4.


The maxinfo router has been deprecated and will be removed in a later release.


The debugcli module has been deprecated and will be removed in 2.4.

New Features

ColumnStore Monitor

The new csmon monitor can be used to monitor ColumnStore clusters where the primary UM will be assigned as the master and secondary UMs as slaves. Automatic detection of the primary UM is supported with ColumnStore versions 1.2.1 and newer. For older versions the primary UM must be designated with the primary parameter of the monitor.

Read the csmon documentation for more information on how to use it.


There is now a new command classify <statement> using which it can be checked if and how MaxScale classifies a specific statement. This feature can be used for debugging, if there is suspicion that MaxScale sends a particular statement to the wrong server (e.g. to a slave when it should be sent to the master).


The global configuration parameter retain_last_statements can now also be specified separately for individual services.


If MaxScale is running as a systemd service, the systemd Watchdog can be enabled and MaxScale will behave accordingly. Please see the documentation for more details.

By default the watchdog is disabled.

NOTE: In 2.3.1 there is a deficiency that manifests itself so that if any administrative operation, performed using maxctrl or maxadmin, takes longer that the specified watchdog timeout, then the watchdog will kill and restart MaxScale. Please take that into account before enabling the watchdog.


  • MXS-2141 Retry read on master when causal_reads timeout is exceeded
  • MXS-2122 Immediately close the listening socket when a listener is destroyed
  • MXS-2077 Provide more information in list clients output.
  • MXS-1976 MaxAdmin Shutting Down A Service should specify / warn that new session requests are neither accepted nor denied.

Bug fixes

  • MXS-2147 Luafilter is missing symbols
  • MXS-2144 Doing a controlled shutdown doesn't trigger query retrying
  • MXS-2142 Default timeout value for causal_reads is excessive
  • MXS-2140 Enabling transaction_replay at runtime doesn't enable implicit parameters
  • MXS-2139 transaction_replay doesn't implicitly enable master_failure_mode=fail_on_write
  • MXS-2136 passwd errors out as a attribute in [monitor] and [service] in maxscale.cnf
  • MXS-2121 Listeners defined in the configuration cannot be destroyed
  • MXS-2109 query_classifier_cache_size is per thread
  • MXS-2107 writeq_high_water doesn't work
  • MXS-2100 Unknown global parameters are not detected
  • MXS-2098 maintenance_on_low_disk_space does not work
  • MXS-2096 SELECT ... INTO OUTFILE is routed to all back end servers
  • MXS-2055 Monitor REST-API documentation
  • MXS-1978 SELECT INTO OUTFILE is routed to all servers

Known Issues and Limitations

There are some limitations and known issues within this version of MaxScale. For more information, please refer to the Limitations document.


RPM and Debian packages are provided for supported the Linux distributions.

Packages can be downloaded here.

Source Code

The source code of MaxScale is tagged at GitHub with a tag, which is identical with the version of MaxScale. For instance, the tag of version X.Y.Z of MaxScale is maxscale-X.Y.Z. Further, the default branch is always the latest GA version of MaxScale.

The source code is available here.


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