# 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](https://jira.mariadb.org). ## 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](../Filters/Masking.md) 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](../Monitors/MariaDB-Monitor.md) 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](../Getting-Started/Configuration-Guide.md#query_classifier_cache_size) 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](../Filters/Cache.md) 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](../Getting-Started/Configuration-Guide.md#events) for details. ### ReadWriteSplit A set of new features have been added to readwritesplit. #### `transaction_replay` The [`transaction_replay`](../Routers/ReadWriteSplit.md#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`](../Routers/ReadWriteSplit.md#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`](../Routers/ReadWriteSplit.md#delayed_retry) parameter allows queries to be automatically retried if their execution is interrupted. #### `causal_reads` The [`causal_reads`](../Routers/ReadWriteSplit.md#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.](https://jira.mariadb.org/issues/?jql=project%20%3D%20MXS%20AND%20issuetype%20%3D%20Bug%20AND%20status%20%3D%20Closed%20AND%20fixVersion%20%3D%202.3.0) ## Known Issues and Limitations There are some limitations and known issues within this version of MaxScale. For more information, please refer to the [Limitations](../About/Limitations.md) document. ## Packaging RPM and Debian packages are provided for the Linux distributions supported by MariaDB Enterprise. Packages can be downloaded [here](https://mariadb.com/resources/downloads). ## 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](https://github.com/mariadb-corporation/MaxScale).