Configuration of MySQLTemTabStTest

In MySQL, a temporary table is a special type of table that allows you to store a temporary result set, which you can reuse several times in a single session. In some cases, the server creates internal temporary tables while processing statements. Users have no direct control over when this occurs. If an internal temporary table is created as an in-memory table but becomes too large, MySQL automatically converts it to an on-disk table. The maximum size for in-memory temporary tables is the minimum of the tmp_table_size and max_heap_table_size. If the result set gets bigger than this threshold, MySQL will overflow to-disk based temporary tables. When the size of on-disk temp tables increases beyond threshold, it can cause disk space exhaustion leading to server outages. Because of the continuous outages of the service, the user has to constantly restart the server leading to poor user experience. MySQLTemTabStTest helps administrators in this regard.

This test continuously tracks the total and maximum number of temporary tables created on disk and alerts administrators when the size of the on-disk temporary tables increases beyond the threshold. This way, administrators can be proactively alerted to increasing size of the on-disk temporary tables and thus enabled to rapidly initiate remedial measures to avoid an impending server outage.

The default parameters associated with this test are:

• The TEST PERIOD list box helps the user to decide how often this test needs to be executed.

• In the HOST text box, specify the HOST for which this test is to be configured.

• In the PORT text box, specify the port at which the target host is listening.

• Specify the name of a database on the target MySQL database server being monitored in the DATABASE textbox.

• The eG agent has to be configured with the credentials of a user who has server-wide Process and Select privileges on the monitored MySQL server. To know how to create such a user, refer to Configuring the eG Agent with Access Privileges topic. Specify the credentials of such a user in the USERNAME and PASSWORD textboxes.

• Confirm the password by retyping it in the CONFIRM PASSWORD textbox.

• By default, the detailed diagnosis of this test, if enabled, will report only the top-10 tables. This is why, the DD ROW COUNT parameter is set to 10 by default. If you want to include more or less tables in detailed diagnosis, then change the value of this parameter accordingly.

• To make diagnosis more efficient and accurate, eG embeds an optional detailed diagnostic capability. With this capability, the eG agents can be configured to run detailed, more elaborate tests as and when specific problems are detected. To enable the detailed diagnosis capability of this test, by default, for a particular server, choose the On option against DETAILED DIAGNOSIS. To disable the capability, click on the Off option.

  The option to selectively enable/disable the detailed diagnosis capability will be available only if the following conditions are fulfilled:

  • The eG manager license should allow the detailed diagnosis capability.

  • Both the bad and normal frequencies configured for the detailed diagnosis measures should not be 0.

• If multiple components of the same component type are awaiting configuration, then an APPLY TO OTHER COMPONENTS button will appear in this page. Clicking on this button will allow you to apply the configuration to all/selected components of that type.

• Once the necessary values have been provided, clicking on the UPDATE button will register the changes made.

When changing the configuration for specific servers, a “*” beside the text box corresponding to the parameter signifies that these values have to be manually configured by the user. The parameter values that require to be configured will typically be prefixed with a “$” or contain a series of “*”. A value of “none” in the parameter value indicates that the corresponding parameter value can be changed if required.