Check mysql-temp-tables

Overview

Checks the number of on-disk versus in-memory temporary tables created in MySQL/MariaDB. Logic is taken from MySQLTuner script:mysql_stats(), v1.9.8.

Hints:

• See additional notes for all mysql monitoring plugins

Fact Sheet

Check Plugin Download	https://github.com/Linuxfabrik/monitoring-plugins/tree/main/check-plugins/mysql-temp-tables
Check Interval Recommendation	Every 15 minutes
Can be called without parameters	Yes
Compiled for	Linux, Windows
Requirements	User with no privileges, locked down to 127.0.0.1 - for example monitoring\@127.0.0.1. Usernames in MySQL/MariaDB are limited to 16 chars in specific versions.
3rd Party Python modules	pymysql

Help

usage: mysql-temp-tables [-h] [-V] [--always-ok]
                         [--defaults-file DEFAULTS_FILE]
                         [--defaults-group DEFAULTS_GROUP] [--timeout TIMEOUT]

Checks the number of on-disk versus in-memory temporary tables created in
MySQL/MariaDB.

options:
  -h, --help            show this help message and exit
  -V, --version         show program's version number and exit
  --always-ok           Always returns OK.
  --defaults-file DEFAULTS_FILE
                        Specifies a cnf file to read parameters like user,
                        host and password from (instead of specifying them on
                        the command line), for example
                        `/var/spool/icinga2/.my.cnf`. Default:
                        /var/spool/icinga2/.my.cnf
  --defaults-group DEFAULTS_GROUP
                        Group/section to read from in the cnf file. Default:
                        client
  --timeout TIMEOUT     Network timeout in seconds. Default: 3 (seconds)

Usage Examples

./mysql-temp-tables --defaults-file=/var/spool/icinga2/.my.cnf

Output:

34.6% temporary tables created on disk (540.0 on disk / 1.6K total)

Recommendations:
* Set tmp_table_size > 128.0MiB and max_heap_table_size > 128.0MiB
* When making adjustments, make tmp_table_size/max_heap_table_size equal
* Reduce your SELECT DISTINCT queries which have no LIMIT clause

States

• WARN if pct_temp_disk (number of on-disk temporary tables) > 25%

Perfdata / Metrics

Name	Type	Description
mysql_created_tmp_disk_tables	Continous Counter	Number of on-disk temporary tables created.
mysql_created_tmp_tables	Continous Counter	Number of in-memory temporary tables created.
mysql_max_heap_table_size	Bytes	Maximum size in bytes for user-created MEMORY tables.
mysql_max_tmp_table_size	Bytes	max(max_heap_table_size, tmp_table_size)
mysql_pct_temp_disk	Percentage	Created_tmp_disk_tables / Created_tmp_tables * 100
mysql_tmp_table_size	Bytes	The largest size for temporary tables in memory (not MEMORY tables) although if max_heap_table_size is smaller the lower limit will apply.

Credits, License

• Authors: Linuxfabrik GmbH, Zurich

• License: The Unlicense, see LICENSE file.

• Credits:

  • heavily inspired by MySQLTuner (https://github.com/major/MySQLTuner-perl)