Variables

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!

Since MariaDB 10.5 we can also see from which file the MariaDB server system variable …

Table of Contents

• Global Options
• Service Options
• Server Options
• Routing Modules
• Listener Options
• Monitor Options
• Filter Options

Global Options

MySQL is well known and widely spread because of its philosophy of Keep it Simple (KISS).

We recently had the discussion that with newer releases also MySQL and MariaDB relational databases becomes more and more complicated.

One indication for this trend is the number of MySQL server system variables and status variables.

In the following tables and graphs we compare the different releases since MySQL version 4.0:

mysql> SHOW GLOBAL VARIABLES;
mysql> SHOW GLOBAL VARIABLES LIKE 'innodb%';
mysql> …

If you are using MariaDB/MySQL 5.5 and newer you should use several InnoDB Buffer Pool Instances for performance reasons.
Some rules to size InnoDB Buffer Pool instances are:

• One InnoDB Buffer Pool Instance should be at least 1 Gibyte in size (innodb_buffer_pool_size / innodb_buffer_pool_instances
  >= 1 Gib).
• InnoDB Buffer Pool Instances you can set equal to the number of cores of your machine.

Binlog format MIXED changes the binary log format (ROW or STATEMENT) depending on the queries (deterministic or not). This makes it impossible to define 100% correctly working binary log filter rules.

If the variable flush_time is set to a non-zero value, all tables are closed (and flushed) every flush_time seconds to disk. This can cause unnecessary and high I/O spikes.

For further information consult MariaDB or MySQL documentation.

The Table Open Cache (table_open_cache or old name table_cache) is a cache to store file handles for all threads. The actual value of cache entries can be seen with the global status of open tables (Open_tables).
Increasing table_open_cache increases the number of file descriptors (open_files_limit) that MySQL requires.
You can check whether you need to increase the Table Open Cache by checking Open_tables and Opened_tables. If the value of Opened_tables is large and you do not use FLUSH TABLES often (which …

The InnoDB Flush Method has changed. This can have an impact on InnoDB write Performance.

InnoDB Buffer Pool

The InnoDB Buffer Pool is the memory area where the InnoDB Storage Engine caches its data and index blocks. Each InnoDB data and index block has a size of Innodb_page_size (16384 byte = 16 kbyte). The InnoDB Buffer Pool is configured in bytes with the innodb_buffer_pool_size variable. On a dedicated system the InnoDB Buffer Pool can be configured up to 80% of the systems physical RAM (free).

The innodb_buffer_pool_awe_mem_mb variable is relevant only on 32-bit Windows systems with more …