MariaDB MaxScale 2.4.0 Release Notes -- 2019-06-29
MariaDB MaxScale 2.4.0 Release Notes -- 2019-06-29
Release 2.4.0 is a Beta release.
This document describes the changes in release 2.4.0, when compared to release 2.3.
For any problems you encounter, please consider submitting a bug report at Jira.
Changed Features
Section and object names
Section and object names starting with @@
are now reserved for
use by MaxScale itself. If any such names are encountered in
configuration files, then MaxScale will not start.
Whitespace in section names that was deprecated in 2.2 will now be rejected and cause the startup of MaxScale to fail.
Binding on network ports
MaxScale 2.4.0 will now use the SO_REUSEPORT capability offered by newer kernels that allows reuse of network listener ports. In practice this means improved connection creation speed with more dynamic balancing of connections.
As a side-effect of this, it is possible for two MaxScale instances to bind on
the same listener port on systems that have Linux kernels newer than 3.9. This
can only happen if the MaxScale instances use completely different directory
structures (i.e. different --basedir
arguments). Normal use of MaxScale still
detects multiple MaxScales trying to bind to the same ports. Almost always, this
will not have any negative side-effects.
Stronger hashing algorithm for admin user passwords
The administrative user passwords are now stored as SHA2-512 hashes which is an improvement over the older MD5 hashing algorithm. New users will use the stronger algorithm but old users will continue using the weaker one. To upgrade administrative users, recreate the user.
REST API
Mandatory protocol
parameter on server creation
The protocol
parameter must now always be defined when a server is
created. The previously undocumented default value of mariadbbackend
now must
be explicitly defined when a server is created via the REST API.
TLS on server creation
To create encrypted connection to a server, the TLS parameters must be defined at server creation time. To enable TLS for a server that doesn't have it, destroy the old one and recreate it afterwards.
Dropped Features
Enabling server TLS via MaxAdmin
As TLS for servers must now be defined at creation time, enabling TLS at runtime via MaxAdmin is no longer possible. Use MaxCtrl to create servers with TLS enabled.
debugcli
and telnetd
The debugcli
router and the telnetd
protocol module it uses have been
removed.
ndbclustermon
The ndbclustermon
module has been removed.
mmmon
The mmmon
module has been removed as the mariadbmon
monitor largely does
what it used to do.
MariaDB-Monitor settings
The following settings have been removed and cause a startup error
if defined: mysql51_replication
, multimaster
and allow_cluster_recovery
.
log_to_shm
The log_to_shm
parameter that was removed in 2.3 will be treated as an unknown
parameter in 2.4.0.
Deprecated Features
mqfilter
The mqfilter
has been deprecated and it will be removed in a future version
of MaxScale.
We advise against using it.
Nagios Plugins
MaxScale no longer ships the example scripts and configuration files for Nagios.
New Features
Clustrix Support
MaxScale now contains support for Clustrix in the form of a Clustrix monitor that is capable of monitoring a Clustrix cluster.
Please see the documentation for details.
Smart Router
MaxScale has now a new router SmartRouter that is capable of routing a query to different kinds of backends, containing the same data, depending on which backend can best handle that particular kind of query.
Please see the documentation for details.
Servers can be drained
It is now possible to drain a server, which means that existing connections to the server can continue to be used but new connections are no longer created to the server.
In the output of maxctrl
, the fact that a server is being drained
is visible in the State
column as the value Draining
.
┌─────────┬─────────────────┬──────┬─────────────┬───────────────────────────────┬───────┐ │ Server │ Address │ Port │ Connections │ State │ GTID │ ├─────────┼─────────────────┼──────┼─────────────┼───────────────────────────────┼───────┤ │ Server1 │ 192.168.121.159 │ 3306 │ 2 │ Master, Running │ 0-1-6 │ ├─────────┼─────────────────┼──────┼─────────────┼───────────────────────────────┼───────┤ │ Server2 │ 192.168.121.80 │ 3306 │ 1 │ Draining, Slave, Running │ 0-1-6 │ ├─────────┼─────────────────┼──────┼─────────────┼───────────────────────────────┼───────┤ │ Server3 │ 192.168.121.122 │ 3306 │ 2 │ Slave, Running │ 0-1-6 │ ├─────────┼─────────────────┼──────┼─────────────┼───────────────────────────────┼───────┤ │ Server4 │ 192.168.121.144 │ 3306 │ 2 │ Slave, Running │ 0-1-6 │ └─────────┴─────────────────┴──────┴─────────────┴───────────────────────────────┴───────┘
A server is set in the Draining state the same way as it is set in the Maintenance state:
$ maxctrl set server Server2 drain
Note that although the state is displayed as Draining
, when setting
and clearing the state, the word drain
is used.
Note that the full implication of draining a server depends upon both on the role of the server and on the router being used, and its configuration.
For instance, if readwritesplit is used and the server being drained
is a slave, then from a client's perspective there will be no difference;
readwritesplit will simply not use that server. However, if the server
being drained is the master, then it will not be possible to connect
unless master_failure_mode
has been set to something else but the
default fail_instantly
.
Once the server has been drained, the state will be Drained
.
weightby
Replacement for Servers: rank
The new rank
parameter is
the replacement for the deprecated weightby
parameter. It allows explicit
groupings of servers into primary and secondary groups. Servers configured with
rank=secondary
will only be used if no primary servers are available.
UNIX Domain Socket for Servers
Servers can now use the
socket
parameter to define
a local UNIX domain socket through which the connections will be created.
Cluster
The servers a service uses can now be specified using the cluster
parameter of the service.
[TheService] ... cluster=TheMonitor
In this case, the servers of the service will be defined by the
referred to monitor. Note that the parameters servers
and cluster
are mutually exclusive.
Durations
In the MaxScale configuration file, durations can now be suffixed with
h
, m
, s
or ms
to indicate that the duration is specified as
hours, minutes, seconds or milliseconds.
Please see the configuration guide for details.
Not providing an explicit unit is strongly discouraged as it will be deprecated in MaxScale 2.5.
Query Classifier Cache
It is now possible to examine the contents of the query classifier cache. The REST-API endpoint is
/v1/maxscale/query_classifier/cache
and the equivalent maxctrl command
maxctrl show qc_cache
The output shows the statements (the canonical version) in the cache, the number of times they have been encountered and how they have been classified.
Connection Attempt Throttling
If a user fails to authenticate multiple times, the host from where the user is
connecting from will be blocked for 60 seconds. See
max_auth_errors_until_block
for more information.
REST API & MaxCtrl
Default API Version
The API version prefix is now optional and if not present, will be assumed to be
the latest version which currently is /v1
.
Hard maintenance mode
The new --force
option for the set server
command in MaxCtrl allows all
connections to the server in question to be closed when it is set into
maintenance mode. This causes idle connections to be closed immediately.
For more information, read the
REST-API documentation for
the set
endpoint.
Command History
The interactive mode for MaxCtrl now has command history.
Multi-parameter Alter
The alter
commands in MaxCtrl now accept multiple key-value pairs in one
command. See output of maxctrl help alter
for more information.
Readwritesplit
For more information on the readwritesplit router, refer to the documentation.
transaction_replay
The transaction replay functionality will now also be applied in conjunction with server initiated transaction rollbacks.
transaction_replay_attempts
The new transaction_replay_attempts
parameter controls how many errors the
transaction replay mechanism tolerates before giving up on the replay
attempt. The number of transaction replay attempts is now capped to a default
value of 5.
lazy_connect
Lazy connection creation delays the opening of all connections until they are needed. This reduces the load that is placed on the backend servers when the client connections are short. This feature is disabled by default.
Connection Selection
The servers where new connections are created at the start of a session are now
always use connection counts. This allows the use of
slave_selection_criteria=LEAST_CURRENT_OPERATIONS
and
max_slave_connections=1
.
Master Selection
Readwritesplit will now load balance master connections in case there are multiple master servers. This is mainly of relevance only with Clustrix clusters.
Maintenance mode
Readwritesplit now allows open transactions to finish if the master is put into
maintenance mode. To forcefully close all connections to a server use the
maxctrl set server <name> maintenance --force
command.
Galeramon
Replicating Slaves
If a slave server is replicating from a Galera node, galeramon will now correctly assign it the Slave status.
GTID in list servers
Galera nodes will now display their GTID positions in the output of
maxctrl list servers
.
Avrorouter Direct Replication
By defining the servers
parameter for the avrorouter service, the replication
is done directly from a remote master server. This skips the binlogrouter
definition completely making the conversion process faster and more space
efficient.
enforce_simple_topology
This MariaDB-Monitor setting allows the monitor greater freedom in managing the backend servers. Please see MariaDB-Monitor documentation for more information.
Bug fixes
Here is a list of bugs fixed in MaxScale 2.4.0.
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.
Packaging
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.