21.9. Performance Schema System Variables

Performance Schema implements several system variables that provide configuration information:

mysql> SHOW VARIABLES LIKE 'perf%';
+---------------------------------------------------+---------+
| Variable_name                                     | Value   |
+---------------------------------------------------+---------+
| performance_schema                                | ON      |
| performance_schema_events_waits_history_long_size | 10000   |
| performance_schema_events_waits_history_size      | 10      |
| performance_schema_max_cond_classes               | 80      |
| performance_schema_max_cond_instances             | 1000    |
| performance_schema_max_file_classes               | 50      |
| performance_schema_max_file_handles               | 32768   |
| performance_schema_max_file_instances             | 10000   |
| performance_schema_max_mutex_classes              | 200     |
| performance_schema_max_mutex_instances            | 1000000 |
| performance_schema_max_rwlock_classes             | 30      |
| performance_schema_max_rwlock_instances           | 1000000 |
| performance_schema_max_table_handles              | 100000  |
| performance_schema_max_table_instances            | 50000   |
| performance_schema_max_thread_classes             | 50      |
| performance_schema_max_thread_instances           | 1000    |
+---------------------------------------------------+---------+

Table 21.1. Performance Schema Variable Reference

NameCmd-LineOption fileSystem VarStatus VarVar ScopeDynamic
performance_schemaYesYesYes GlobalNo
Performance_schema_cond_classes_lost   YesGlobalNo
Performance_schema_cond_instances_lost   YesGlobalNo
performance_schema_events_waits_history_long_sizeYesYesYes GlobalNo
performance_schema_events_waits_history_sizeYesYesYes GlobalNo
Performance_schema_file_classes_lost   YesGlobalNo
Performance_schema_file_handles_lost   YesGlobalNo
Performance_schema_file_instances_lost   YesGlobalNo
Performance_schema_locker_lost   YesGlobalNo
performance_schema_max_cond_classesYesYesYes GlobalNo
performance_schema_max_cond_instancesYesYesYes GlobalNo
performance_schema_max_file_classesYesYesYes GlobalNo
performance_schema_max_file_handlesYesYesYes GlobalNo
performance_schema_max_file_instancesYesYesYes GlobalNo
performance_schema_max_mutex_classesYesYesYes GlobalNo
performance_schema_max_mutex_instancesYesYesYes GlobalNo
performance_schema_max_rwlock_classesYesYesYes GlobalNo
performance_schema_max_rwlock_instancesYesYesYes GlobalNo
performance_schema_max_table_handlesYesYesYes GlobalNo
performance_schema_max_table_instancesYesYesYes GlobalNo
performance_schema_max_thread_classesYesYesYes GlobalNo
performance_schema_max_thread_instancesYesYesYes GlobalNo
Performance_schema_mutex_classes_lost   YesGlobalNo
Performance_schema_mutex_instances_lost   YesGlobalNo
Performance_schema_rwlock_classes_lost   YesGlobalNo
Performance_schema_rwlock_instances_lost   YesGlobalNo
Performance_schema_table_handles_lost   YesGlobalNo
Performance_schema_table_instances_lost   YesGlobalNo
Performance_schema_thread_classes_lost   YesGlobalNo
Performance_schema_thread_instances_lost   YesGlobalNo

The variables have the following meanings:

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