MaxScale MariaDB Protocol Module

Overview

The mariadbprotocol module implements the MariaDB client-server protocol.

The legacy protocol names mysqlclient, mariadb and mariadbclient are all aliases to mariadbprotocol.

Connection Redirection

The Connection Redirection introduced in MariaDB 11.4 allows client connections to be redirected to another server if the server in question is going into maintenance. As MaxScale is intended to be the gateway through which clients connect to the database cluster, the use of redirect_url directly on the backend database servers poses some challenges when used with MaxScale.

To prevent the accidental redirection of clients away from MaxScale, the notification about the change of the system variable redirect_url is intercepted by MaxScale and renamed into mxs_rdir_url. This prevents any automated redirects from taking place while still allowing clients to see the information if they need it.

To redirect clients away from MaxScale, use the redirect_url parameter.

Configuration

Protocol level parameters are defined in the listeners. They must be defined using the scoped parameter syntax where the protocol name is used as the prefix.

[MyListener]
type=listener
service=MyService
protocol=mariadbprotocol
mariadbprotocol.allow_replication=false
port=3306

For the MariaDB protocol module, the prefix is always mariadbprotocol.

Settings

allow_replication

• Type: boolean

• Mandatory: No

• Dynamic: Yes

• Default: true

Whether the use of the replication protocol is allowed through this listener. If disabled with mariadbprotocol.allow_replication=false, all attempts to start replication will be rejected with a ER_FEATURE_DISABLED error (error number 1289).

compression

• Type: enum_mask

• Mandatory: No

• Dynamic: Yes

• Values: none, zlib, zstd

• Default: zlib, zstd

The set of enabled compression protocols. The zlib compression protocol is the traditional MySQL/MariaDB zlib based compression algorithm that uses a fixed compression level. The zstd is the newer compression protocol that allows the compression level to be configured by the client.

To disable protocol level compression, set mariadbprotocol.compression=none.

compression_threshold

• Type: size

• Mandatory: No

• Dynamic: Yes

• Default: 50

The upper limit for uncompressed payloads.

In MariaDB and MySQL, the upper limit for uncompressed payloads is always 50 bytes. If the response is smaller than that, the result is sent uncompressed and if it's larger than that, it is sent compressed. MaxScale allows this limit to be configured so that larger results can be sent uncompressed.

For example, with mariadbprotocol.compression_threshold=256Ki, only events that are larger than 256 kibibytes get compressed. Most small resultsets thus will be sent uncompressed but larger ones will be compressed before being sent. This makes it possible to customize the bandwidth usage of MaxScale when protocol level compression is used.

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