MariaDB MaxScale 2.2.0 Release Notes -- 2017-10-12

MariaDB MaxScale 2.2.0 Release Notes -- 2017-10-12

Release 2.2.0 is a Beta release.

This document describes the changes in release 2.2.0, when compared to release 2.1.

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

Changed Features

Whitespace in Object Names

Significant whitespace in object names is now deprecated. All object names (services, servers, etc.) will be converted to a compatible format by squeezing repeating whitespace and replacing it with hyphens. If any object name conversions take place, a warning will be logged.

Monitor Scripts

The execution of monitor scripts has been made synchronous. This means that a monitor will wait until the executed script is done or until a timeout is exceeded. The timeout is configurable with the script_timeout parameter.

In addition to this, the output of the script is logged into the MaxScale log file. The message is logged on the matching log level if it is prefixed with one of alert:, error:, warning:, notice:, info: or debug:. If no prefix is provided, the message is logged on the notice level.

For more information, refer to the monitor documentation.

Read-only Administrative Users

Users that can only perform read-only operations can be created with add readonly-user and enable readonly-account commands. To convert administrative users to read-only users, delete the old administrative user and create it as a read-only user.

For more information about administrative interface users, refer to the MaxAdmin documentation.

Note: Old users from pre-2.2 MaxScale versions will be converted to administrative users that have full access to all commands.


The remove user command now only expects one parameter, the username.

Regular Expression Parameters

Modules may now use a built-in regular expression (regex) string parameter type instead of a normal string when accepting patterns. The regex parameters are checked by the config file loader to compile using the PCRE2 library embedded within MaxScale. The only module using the new regex parameter type is currently QLAFilter.

The only action users should take is enclose their regular expressions in slashes, e.g. match=/^select/ defines the pattern ^select. The slashes allow whitespace to be read from the ends of the regex string contrary to a normal string parameter and are removed before compiling the pattern. For backwards compatibility, the slashes are not yet mandatory. Omitting them is, however, deprecated and will be rejected in the next release of MaxScale.


The default value of monitor_interval was changed from 10000 milliseconds to 2000 milliseconds.


The filter now accepts multiple match-server pairs. Please see the NamedServerFilter documentation for details.

Tee Filter

The tee filter has been rewritten to better suit the way MaxScale now functions. The filter requires that the service where the branched session is created has at least one network listener. The users must also be able to connect from the local MaxScale host. Usually this means that an extra grant for the loopback address is required (e.g. myuser@

In addition to the aforementioned requirements, a failure to create a branched session no longer causes the actual client session to be closed. In most cases, this is desired behavior.

The match and exclude parameters were changed to use PCRE2 syntax for the regular expressions. The regular expression should be enclosed by slashes e.g. match=/select.*from.*test/.

A tee filter instance can be disabled with the new tee disable [FILTER] and tee enable [FILTER] module commands. Refer to the module command documentation for more details on module commands and the Tee Filter documentation for details on the tee filter specific commands.


The function type rule will now match a query that does not use a function when the filter is in whitelist mode (action=allow). This means that queries that don't use functions are allowed though in whitelist mode.

Rule Names

Rule names can no longer use punctuation in them and can consist only of alphanumeric characters, underscores and hyphens.

Keywords deny and allow

The deny and allow keywords are deprecated in favor of the more descriptive match keyword. All instances of deny and allow can be replaced with match with no functional changes.


When known, the session id will be included in all logged messages. This allows a range of logged messages related to a particular session (that is, client) to be bound together, and makes it easier to investigate problems. In practice this is visible so that if a logged message earlier looked like

2017-08-30 12:20:49   warning: [masking] The rule ...

it will now look like

2017-08-30 12:20:49   warning: (4711) [masking] The rule ...

where 4711 is the session id.

Binlogrouter Default Values

The binlogdir now has a default value of /var/lib/maxscale/. Previously the parameter was mandatory even though it was documented to have a default value.

The mariadb10-compatibility is enabled by default since MaxScale 2.2.0. This allows easier use of the MariaDB 10 series server.

Dropped Features


The following deprecated commands have been removed:

  • enable log [debug|trace|message]
  • disable log [debug|trace|message]
  • enable sessionlog [debug|trace|message]
  • disable sessionlog [debug|trace|message]

The following commands have been deprecated:

  • enable sessionlog-priority <session-id> [debug|info|notice|warning]
  • disable sessionlog-priority <session-id> [debug|info|notice|warning]
  • reload config

The { enable | disable } sessionlog-priority commands can be issued, but they have no effect.

Filenames as MaxAdmin Arguments

MaxAdmin no longer attempts to interpret additional command line parameters as a file name to load commands from (e.g. maxadmin mycommands.txt). The shell indirection operator < should be used to achieve the same effect (maxadmin < mycommands.txt).

New Features


MariaDB MaxScale now exposes a REST-API for obtaining information about and for manipulating the resources of MaxScale. For more information please refer to the REST API documentation.

MaxCtrl Command Line Client

The MaxCtrl is a new command line intended to replace MaxAdmin. This client uses the REST API to communicate with MaxScale in a secure way. The client is distributed separately in the maxscale-client package.

For more information, refer to the MaxCtrl documentation.

Limited support from Pluggable Authentication Modules (PAM).

Pluggable authentication module (PAM) is a general purpose authentication API. An application using PAM can authenticate a user without knowledge about the underlying authentication implementation. For more information please refer to the PAM Authenticator documentation.

MySQL Monitor Crash Safety

The MySQL monitor keeps a journal of the state of the servers and the currently elected master. This information will be read if MaxScale suffers an uncontrolled shutdown. By doing the journaling of server states, the mysqlmon monitor is able to keep track of stale master and stale slave states across restarts and crashes.

New Variables for Monitor Scripts

The PARENT and CHILDREN variables were added to the monitor scripts. The former expands to the direct parent node of the server that triggers the event and the latter expands to a list of servers that are direct descendants of the server that triggered the event.

For more information, refer to the monitor documentation.

Avrorouter deflate compression

The Avrorouter now supports the deflate compression method. This allows the stored Avro format files to be compressed on disk. For more information, refer to the Avrorouter documentation.

Preliminary proxy protocol support

The MySQL backend protocol module now supports sending a proxy protocol header to the server. For more information, see the server section in the Configuration guide.

KILL command support

The MySQL client protocol now supports execution of KILL statements through MaxScale. The connection IDs in these queries will be transformed into the correct ones by MaxScale.

KILL QUERY ID <query_id> is not supported by MaxScale and it needs to be executed directly on the relevant backend server. In addition to this, there are minor limitations to the KILL command handling. See Limitations for more information.

Obfuscation and partial masking added to the masking filter.

A value can now be obfuscated instead of just masked. Further, it is possible to specify with a regular expression that only a specific part of a value should be masked. For more information, please read the masking filter documentation.

New rules for dbfwfilter

The uses_function type rule prevents certain columns from being used with functions. It is now also possible to match a function if it is used in conjunction with specific columns. For more information about the new rules, read the dbfwfilter documentation.

Bug fixes

Here is a list of bugs fixed in MaxScale 2.2.0.

  • MXS-1450 Maxadmin commands with a leading space are silently ignored
  • MXS-1449 Database change not allowed
  • MXS-1405 Script launched by monitors should run synchronously
  • MXS-1397 ReadWriteSplit's master connection can time out if session only issues read-only queries
  • MXS-1359 qc_sqlite crashes with a very large compound select
  • MXS-1351 Partially authenticated connections are put into the connection pool
  • MXS-1349 qc_mysqlembedded accesses wrong preparable statement field
  • MXS-1346 Function blocking per column
  • MXS-1345 Empty function list is not allowed
  • MXS-1340 Report true table and not alias name
  • MXS-1339 QC should return a particular table/database just once
  • MXS-1334 Build on FreeBSD 11 looks for libdl - how can it be told not to?
  • MXS-1322 Flushing log should reopen not reopen and truncate.
  • MXS-1307 Add CTE tests
  • MXS-1265 strerror_r calls result in compiler warnings
  • MXS-1262 Mantenance bit(s) should persist after maxscale restart
  • MXS-1221 Nagios plugin scripts does not process -S option properly
  • MXS-1214 Streaming Insert Filter gives errors
  • MXS-1203 Batch inserts through Maxscale with C/J stall
  • MXS-1198 Interface retry bind interval (of a listener) increases by ten seconds every time it fails (10,20,30,....) it should be a fixed interval (and maybe configurable)
  • MXS-1160 Load infile not working on Schemarouter
  • MXS-1146 JDBC connection dropping transaction when connecting to MaxScale directly
  • MXS-959 KILL command on wrong connection ID

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 the Linux distributions supported by MariaDB Enterprise.

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 X.Y.Z. Further, master always refers to the latest released non-beta version.

The source code is available here.


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