configuration

Table of contents

• Overview
• Preparations
• Activate MaxScale configuration synchronisation
• Change MaxScale parameters
• Add new slave and make MaxScale known
• Remove old slave and make MaxScale known
• How is the configuration synchronised?

Inhaltsverzeichnis

• Übersicht
• Vorbereitungen
• MaxScale Konfigurations-Synchronisation aktivieren
• MaxScale Parameter ändern
• Neuer Slave hinzufügen und MaxScale bekannt machen
• Alter Slave entfernen und MaxScale bekannt machen

If we do customers database configuration analysis we check on one side if the most important MariaDB server system variables (innodb_buffer_pool_size, ...) are set appropriately but also if some MariaDB server system variables are configured completely wrong.

Fortunately MariaDB introduced in MariaDB 10.1 the INFORMATION_SCHEMA.SYSTEM_VARIABLES view where you can find all the relevant information. But one!

How many connections can be opened concurrently against my MySQL or MariaDB database can be configured and checked with the following command:

SHOW GLOBAL VARIABLES LIKE 'max_connections';
+-----------------+-------+
| Variable_name   | Value |
+-----------------+-------+
| max_connections | 505   |
+-----------------+-------+

If this limit was ever reached in the past can be checked with:

If you ask around about shared hosting setups with MySQL everybody is frightened. In fact it looks like shared hosting is one of the most difficult setups you can get.

The number of users is big, the number of tables huge and the load pattern is completely unpredictable and the queries often very, let us say: non-optimal.

Here one of the DBA wisdoms come into play: Controlling developers is like herding cats.

If you talk to the Shared MySQL Hoster they confirm that this setups are very demanding!

MySQL Cluster is mainly an in-memory database. Nevertheless it requires a good I/O system for writing various different information to disk.

The information MySQL Cluster writes to disk are the:

• Global Checkpoints (GCP) which are the transactions.
• Local Checkpoints (LCP) which is a dirty image of the data.
• Backup.

In the following schema (a 2-node Cluster) you can see what is related to each other: