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https://dev.mysql.com/doc/refman/8.4/en/performance-schema-objects-summary-global-by-type-table.html
The Performance Schema maintains the objects_summary_global_by_type table for aggregating object wait events. Example object wait event summary information: mysql> SELECT * FROM performance_schema.objects_summary_global_by_type\G ... row ...
https://dev.mysql.com/doc/refman/8.4/en/performance-schema-optimization.html
Applications that monitor databases may make frequent use of Performance Schema tables. To write queries for these tables most efficiently, take advantage of their indexes. For example, include a WHERE clause that restricts retrieved rows based on ...
https://dev.mysql.com/doc/refman/8.4/en/performance-schema-performance-timers-table.html
For an explanation of how event timing occurs, see Section 29.4.1, “Performance Schema Event Timing”. For a cycle timer, the frequency is generally related to the CPU speed. For example, on a system with a 2.4GHz processor, the CYCLE may be ...
https://dev.mysql.com/doc/refman/8.4/en/performance-schema-replication-group-communication-information-table.html
This table shows group configuration options for the whole replication group. The replication_group_communication_information table has these columns: WRITE_CONCURRENCY The maximum number of consensus instances that the group can execute in ...
https://dev.mysql.com/doc/refman/8.4/en/performance-schema-restrictions.html
The Performance Schema avoids using mutexes to collect or produce data, so there are no guarantees of consistency and results can sometimes be incorrect. If you save event information in another table, you should not assume that the original events ...
https://dev.mysql.com/doc/refman/8.4/en/performance-schema-runtime-configuration.html
Specific Performance Schema features can be enabled at runtime to control which types of event collection occur. 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 29.12.2, “Performance Schema Setup ...
https://dev.mysql.com/doc/refman/8.4/en/performance-schema-setup-consumers-table.html
For detailed information about the effect of enabling different consumers, see Section 29.4.7, “Pre-Filtering by Consumer”. If you disable a consumer, the server does not spend time adding event information to it. The setup_consumers table has ...
https://dev.mysql.com/doc/refman/8.4/en/performance-schema-setup-instruments-table.html
The setup_instruments table lists classes of instrumented objects for which events can be collected: mysql> SELECT * FROM performance_schema.setup_instruments\G *************************** 1. row *************************** NAME: ...
https://dev.mysql.com/doc/refman/8.4/en/performance-schema-setup-meters-table.html
This column can be modified DESCRIPTION: A string describing the meter.
https://dev.mysql.com/doc/refman/8.4/en/performance-schema-setup-metrics-table.html
The setup_metrics table lists the available metrics: mysql> select * from performance_schema.setup_metrics\G *************************** 34. row *************************** NAME: undo_tablespaces_active METER: mysql.inno METRIC_TYPE: ASYNC GAUGE ...