MaxScale/Documentation/Release-Notes/MaxScale-2.3.0-Release-Notes.md

MariaDB MaxScale 2.3.0 Release Notes

Release 2.3.0 is a Beta release.

This document describes the changes in release 2.3.0, when compared to release 2.2.

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

Changed Features

MaxCtrl create monitor

The create monitor command now accepts a list of key-value parameters that are passed to the monitor as the last argument. This allows creation and configuration of monitors in one command.

query_retries

The default value of query_retries was changed from 0 to 1. This turns on failure tolerant queries for monitors and authenticators which prevents failures due to network problems. A single reconnection attempt is made to keep responsiveness high even with default values.

Session Command History

The readwritesplit session command history is now enabled mby default but it is limited to a total of 50 distict session commands. This default allows most sessions to leverage the newly improved reconnection mechanism without having to explicitly enable the history. When the limit of 50 commands is exceeded, the session command history is disabled. This makes it possible to use pooled connections by default without having to explicitly disable the history (this was the case with pre-2.1 versions of MaxScale).

The way that the history is stored has also changed. Instead of storing all session commands, each session only stores the first and last execution of each command. This way the history is compressed into a compact representation while still retaining the relative order of each command.

To keep the old functionality, add disable_sescmd_history=true to the service definition.

Masking Filter

By default the masking filter rejects statements that use functions on conjuction with columns that should be masked. Please see the Masking Filter documentation for details.

router_options in Binlogrouter

The use of router_options with the binlogrouter module is deprecated in MaxScale 2.3 and will be removed in a subsequent release. The router_options should be converted into separate parameters.

thread_stack_size

The thread_stack_size configuration parameter is ignored and has been deprecated. If you need to explicitly set the stack size, do so using ulimit -s before starting MaxScale.

ssl for Servers and Listeners

The ssl parameter now accepts boolean values ìn addition to the old required and disabled values.

MariaDBMonitor

MariaDBMonitor has undergone several changes listed briefly below. Please see MariaDBMonitor documentation for more details.

JSON diagnostics output changed

The data in the diagnostic output of the REST-API has changed, with some fields removed and others added.

Master detection

The monitor is now less likely to suddenly change the master server, even if another server has more slaves than the current master. The DBA can force a master reselection by setting the current master read-only, or by removing all its slaves if the master is down.

Only one server can have the Master status flag at a time, even in a multimaster setup. Others servers in the multimaster group are given the Relay Master and Slave status flags.

Switchover new master autoselection

The switchover command can now be called with just the monitor instance name as parameter. In this case the monitor will automatically select a server for promotion.

Replication lag detection

The replication lag measurement now simply reads the Seconds_Behind_Master-field of the slave status output of slaves. The slave calculates this value by comparing the time stamp in the binlog event the slave is currently processing to the slave's own clock. If a slave has multiple slave connections, the smallest lag is used.

Low disk space detection, automatic switchover

With recent MariaDB Server versions, the monitor can check the disk space on the backends and detect if the server is running low. The monitor can be set to automatically switchover a master low on disk space. Slaves are instead set to maintenance mode.

Unused parameters

The following parameters are unused and are ignored if set:

• mysql51_replication MySQL5.1 is no longer supported.
• multimaster The monitor now always detects multimaster setups.
• allow_cluster_recovery Now always on.
• detect_replication_lag Lag detection no longer writes to databases so it is always on.

Dropped Features

log_to_shm parameter and --log=shm option

The following commands no longer create the log files in shared memory and will be ignored. MaxScale will behave as if --log=file was provided when --log=shm is used. The log_to_shm parameter is ignored. Both the parameter and the optino value are deprecated and will be removed in a later relesae.

Logs can still be created in shared memory by pointing logdir to /dev/shm.

Configuration Reloading

The deprecated maxadmin reload config command has been removed.

router_options in Avrorouter

The use of router_options with avrorouter was deprecated in MaxScale 2.1. In MaxScale 2.3, the use of router_options is no longer supported and the options should be given as parameters instead.

router_options in readwritesplit

The use of router_options with readwritesplit, which was deprecated in MaxScale 2.2.0, has been removed in MaxScale 2.3.0.

QUERY-LAST-TRANSACTION and QUERY-TRANSACTION CDC commands

The CDC protocol no longer accepts the QUERY-LAST-TRANSACTION and QUERY-TRANSACTION commands. They were removed due to the addition of the REST API that provides the same information in a more easy to process format.

New Features

Query Classifier Cache

The query classifier now caches the results of each classification which significantly improves performance of workloads that require query classification. The default cache size limit is 40% of total system memory.

Read the configuration guide for more information about the details of the query classifier cache and how to configure it.

Runtime Configuration of the Cache

With the variable @maxscale.cache.enabled it is now possible for a client to specify whether the cache should be used. Please see the Cache documentation for details.

User Specified Syslog Facility and Level for Authentication Errors

It is now possible for the end user to specify the syslog facility and level for authentication errors. Please see the configuration guide for details.

ReadWriteSplit

A set of new features have been added to readwritesplit.

transaction_replay

The transaction_replay parameter enables replaying of transactions if a master server is lost mid-transaction. This allows transparent replacement of master servers with a minimal amount of failed transactions.

master_reconnection

With the master_reconnection parameter, if the connection to a master server is lost or the master server changes, readwritesplit can now reconnect seamlessly to the master server without losing the session state.

delayed_retry

The delayed_retry parameter allows queries to be automatically retried if their execution is interrupted.

causal_reads

The causal_reads parameter enables distributed consistent reads with MariaDB version 10.2 and newer.

Interactive Mode for MaxCtrl

MaxCtrl can now be started in an interactive mode similar to MaxAdmin. This makes use of passwords more convenient as they have to be input only once and they are cached for the duration of the session.

For more information about MaxCtrl, see the output of maxctrl help.

Bug fixes

Here is a list of bugs fixed in MaxScale 2.3.0.

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.