200 lines
8.5 KiB
Markdown
200 lines
8.5 KiB
Markdown
# MariaDB MaxScale 2.4.0 Release Notes
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Release 2.4.0 is a Beta release.
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This document describes the changes in release 2.4.0, when compared to
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release 2.3.
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For any problems you encounter, please consider submitting a bug
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report at [Jira](https://jira.mariadb.org).
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## Changed Features
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### Section and object names
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Section and object names starting with `@@` are now reserved for
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use by MaxScale itself. If any such names are encountered in
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configuration files, then MaxScale will not start.
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Whitespace in section names that was deprecated in 2.2 will now be
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rejected and cause the startup of MaxScale to fail.
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### Binding on network ports
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MaxScale 2.4.0 will now use the SO_REUSEPORT capability offered by newer kernels
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that allows reuse of network listener ports. In practice this means improved
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connection creation speed with more dynamic balancing of connections.
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As a side-effect of this, it is possible for two MaxScale instances to bind on
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the same listener port on systems that have Linux kernels newer than 3.9. This
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can only happen if the MaxScale instances use completely different directory
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structures (i.e. different `--basedir` arguments). Normal use of MaxScale still
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detects multiple MaxScales trying to bind to the same ports. Almost always, this
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will not have any negative side-effects.
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### Maintenance mode and Readwritesplit
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Readwritesplit now allows open transactions to finish if the master is put into
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maintenance mode. To forcefully close all connections to a server use the
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`maxctrl set server <name> maintenance --force` command.
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### Stronger hashing algorithm for admin user passwords
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The administrative user passwords are now stored as SHA2-512 hashes which is an
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improvement over the older MD5 hashing algorithm. New users will use the
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stronger algorithm but old users will continue using the weaker one. To upgrade
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administrative users, recreate the user.
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## Dropped Features
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### `debugcli` and `telnetd`
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The `debugcli` router and the `telnetd` protocol module it uses have been
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removed.
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### `ndbclustermon`
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The `ndbclustermon` module has been removed.
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### `mmmon`
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The `mmmon` module has been removed as the `mariadbmon` monitor largely does
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what it used to do.
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## New Features
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### Servers can be drained
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It is now possible to drain a server, which means that existing
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connections to the server can continue to be used but new connections
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are no longer created to the server.
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In the output of `maxctrl`, the fact that a server is being drained
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is visible in the `State` column as the value `Draining`.
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```
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┌─────────┬─────────────────┬──────┬─────────────┬───────────────────────────────┬───────┐
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│ Server │ Address │ Port │ Connections │ State │ GTID │
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├─────────┼─────────────────┼──────┼─────────────┼───────────────────────────────┼───────┤
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│ Server1 │ 192.168.121.159 │ 3306 │ 2 │ Master, Running │ 0-1-6 │
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├─────────┼─────────────────┼──────┼─────────────┼───────────────────────────────┼───────┤
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│ Server2 │ 192.168.121.80 │ 3306 │ 1 │ Draining, Slave, Running │ 0-1-6 │
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├─────────┼─────────────────┼──────┼─────────────┼───────────────────────────────┼───────┤
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│ Server3 │ 192.168.121.122 │ 3306 │ 2 │ Slave, Running │ 0-1-6 │
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├─────────┼─────────────────┼──────┼─────────────┼───────────────────────────────┼───────┤
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│ Server4 │ 192.168.121.144 │ 3306 │ 2 │ Slave, Running │ 0-1-6 │
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└─────────┴─────────────────┴──────┴─────────────┴───────────────────────────────┴───────┘
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```
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A server is set in the _Draining_ state the same way as it is
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set in the _Maintenance_ state:
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```
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$ maxctrl set server Server2 drain
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```
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Note that although the state is displayed as `Draining`, when setting
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and clearing the state, the word `drain` is used.
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Note that the full implication of draining a server depends upon
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both on the role of the server and on the router being used, and its
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configuration.
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For instance, if readwritesplit is used and the server being drained
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is a slave, then from a client's perspective there will be no difference;
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readwritesplit will simply not use that server. However, if the server
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being drained is the master, then it will not be possible to connect
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unless `master_failure_mode` has been set to something else but the
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default `fail_instantly`.
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Once the server has been drained, the state will be `Drained`.
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### Cluster
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The servers a service uses can now be specified using the `cluster`
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parameter of the service.
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```
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[TheService]
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...
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cluster=TheMonitor
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```
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In this case, the servers of the service will be defined by the
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referred to monitor. Note that the parameters `servers` and `cluster`
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are mutually exclusive.
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### Durations
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In the MaxScale configuration file, durations can now be suffixed with
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`h`, `m`, `s` or `ms` to indicate that the duration is specified as
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hours, minutes, seconds or milliseconds.
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Please see the
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[configuration guide](../Getting-Started/Configuration-Guide.md#durations)
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for details.
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_Not_ providing an explicit unit is strongly discouraged as it will be
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deprecated in MaxScale 2.5.
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### Query Classifier Cache
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It is now possible to examine the contents of the query classifier cache.
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The REST-API endpoint is
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```
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/v1/maxscale/query_classifier/cache
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```
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and the equivalent _maxctrl_ command
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```
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maxctrl show qc_cache
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```
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The output shows the statements (the canonical version) in the cache,
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the number of times they have been encountered and how they have been
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classified.
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### REST API & MaxCtrl: Hard maintenance mode
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The new `--force` option for the `set server` command in MaxCtrl allows all
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connections to the server in question to be closed when it is set into
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maintenance mode. This causes idle connections to be closed immediately.
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For more information, read the
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[REST-API](../REST-API/Resources-Server.md#set-server-state) documentation for
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the `set` endpoint.
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### Readwritesplit
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For more information on the readwritesplit router, refer to the
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[documentation](../Routers/ReadWriteSplit.md).
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#### `transaction_replay_attempts`
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The new `transaction_replay_attempts` parameter controls how many errors the
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transaction replay mechanism tolerates before giving up on the replay
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attempt. The number of transaction replay attemps is now capped to a default
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value of 5.
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#### `lazy_connect`
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Lazy connection creation delays the opening of all connections until they are
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needed. This reduces the load that is placed on the backend servers when the
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client connections are short. This feature is disabled by default.
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## Bug fixes
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[Here is a list of bugs fixed in MaxScale 2.4.0.](https://jira.mariadb.org/issues/?jql=project%20%3D%20MXS%20AND%20issuetype%20%3D%20Bug%20AND%20status%20%3D%20Closed%20AND%20fixVersion%20%3D%202.4.0)
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## Known Issues and Limitations
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There are some limitations and known issues within this version of MaxScale.
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For more information, please refer to the [Limitations](../About/Limitations.md) document.
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## Packaging
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RPM and Debian packages are provided for the Linux distributions supported
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by MariaDB Enterprise.
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Packages can be downloaded [here](https://mariadb.com/resources/downloads).
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## Source Code
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The source code of MaxScale is tagged at GitHub with a tag, which is identical
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with the version of MaxScale. For instance, the tag of version X.Y.Z of MaxScale
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is X.Y.Z. Further, *master* always refers to the latest released non-beta version.
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The source code is available [here](https://github.com/mariadb-corporation/MaxScale).
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