Performance Schema Runtime Configuration many sizing parameters need not be set at all. To see which parameters are autosized or autoscaled, use mysqld --verbose --help  and examine the option descriptions, or see Section 27.15, “Performance Schema System Variables” . For each autosized parameter that is not set at server startup, the Performance Schema determines how to set its value based on the value of the following system values, which are considered as “hints”  about how you have configured your MySQL server: To override autosizing or autoscaling for a given parameter, set it to a value other than  − 1 at startup. In this case, the Performance Schema assigns it the specified value. At runtime,  SHOW VARIABLES  displays the actual values that autosized parameters were set to. Autoscaled parameters display with a value of  − 1. If the Performance Schema is disabled, its autosized and autoscaled parameters remain set to  − 1 and SHOW VARIABLES  displays  − 1. Specific Performance Schema features can be enabled at runtime to control which types of event collection occur. Performance Schema setup tables contain information about monitoring configuration: You can examine the contents of these tables to obtain information about Performance Schema monitoring characteristics. If you have the  UPDATE  privilege, you can change Performance Schema operation by modifying setup tables to affect how monitoring occurs. For additional details about these tables, see Section 27.12.2, “Performance Schema Setup Tables” . The  setup_instruments  and  setup_consumers  tables list the instruments for which events can be collected and the types of consumers for which event information actually is collected, respectively. Other setup tables enable further modification of the monitoring configuration. Section 27.4.2, “Performance Schema Event Filtering” , discusses how you can modify these tables to affect event collection. If there are Performance Schema configuration changes that must be made at runtime using SQL statements and you would like these changes to take effect each time the server starts, put the statements in a file and start the server with the  init_file  system variable set to name the file. This strategy can also be useful if you have multiple monitoring configurations, each tailored to produce a different kind of monitoring, such as casual server health monitoring, incident investigation, application behavior 27.4 Performance Schema Runtime Configuration max_connections open_files_limit table_definition_cache table_open_cache mysql>  SELECT TABLE_NAME FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_SCHEMA = ’performance_schema’ AND TABLE_NAME LIKE ’setup%’; +-------------------+ | TABLE_NAME | +-------------------+ | setup_actors | | setup_consumers | | setup_instruments | | setup_objects | | setup_threads | +-------------------+ 4904