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Metrics for scalability measurement

Note

This feature has been deprecated in Percona Server for MySQL Percona Server for MySQL 5.7.16-10. Users who have installed this plugin but are not using its capability are advised to uninstall the plugin due to known crashing bugs.

Percona Server for MySQL has implemented extra scalability metrics. These metrics allow using Little’s Law, queuing theory, and Universal Scalability Law to gain insights into server performance. This feature is implemented as a plugin.

Installation

Scalability Metrics plugin is shipped with Percona Server for MySQL, but it is not installed by default. To enable the plugin you must run the following command:

INSTALL PLUGIN scalability_metrics SONAME 'scalability_metrics.so';

You can check if the plugin is loaded correctly by running:

SHOW PLUGINS;

The plugin should be listed in the output:

+--------------------------------+----------+--------------------+------------------------+---------+
| Name                           | Status   | Type               | Library                | License |
+--------------------------------+----------+--------------------+------------------------+---------+
...
| scalability_metrics            | ACTIVE   | AUDIT              | scalability_metrics.so | GPL     |
+--------------------------------+----------+--------------------+------------------------+---------+

System Variables

scalability_metrics_control

Option Description
Command-line Yes
Scope Global
Dynamic Yes
Data type String
Default OFF
Values OFF, ON, RESET

This variable can be used to enable and disable the collection of metrics for scalability measurement. By setting the value to RESET all counters will be reset while continuing to count metrics.

Status Variables

scalability_metrics_elapsedtime

Option Description
Data type Numeric

This status variable shows total time elapsed, in microseconds, since metrics collection was started.

scalability_metrics_queries

Option Description
Data type Numeric

This status variable shows number of completed queries since metrics collection was started.

scalability_metrics_concurrency

Option Description
Data type Numeric

This status variable shows number of queries currently executed.

scalability_metrics_totaltime

Option Description
Data type Numeric

This status variable shows total execution time of all queries, including the in-progress time of currently executing queries, in microseconds (ie. if two queries executed with 1 second of response time each, the result is 2 seconds).

scalability_metrics_busytime

Option Description
Data type Numeric

This counter accounts the non-idle server time, that is, time when at least one query was executing.

Version Specific Information

  • Percona Server for MySQL 5.7.10-1: Feature ported from Percona Server for MySQL 5.6

  • Percona Server for MySQL 5.7.16-10: Feature has been deprecated.

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