Status

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> …

When analysing MySQL configuration and status information at customers it is always interesting to see how the applications behave. This can partially be seen by the output of the SHOW GLOBAL STATUS command. See also Reading MySQL fingerprints.

Today we wanted to know where the high Com_create_table and the twice as high Com_drop_table is coming from. One suspect was TEMPORARY TABLES. But are real temporary tables counted as Com_create_table and Com_drop_table at all? This is what we want to find out today. …

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 …

Because I do a lot of Performance Tuning gigs I get often in contact with these status variables. In the beginning I had a problem to understand them and now I have a problem to memorize the relation of the name and the meaning. Therefore I wrote this little summary:

Prepare the example

To show you the effect I have worked out a little example:

CREATE TABLE test (
    id    INT UNSIGNED NOT NULL AUTO_INCREMENT PRIMARY KEY
  , data  VARCHAR(32)
  , ts    TIMESTAMP
  , INDEX (data)
);

INSERT INTO test
VALUES …