The Performance Schema implements several system variables that provide configuration information:
mysql> SHOW VARIABLES LIKE 'perf%';
+----------------------------------------------------------+-------+
| Variable_name | Value |
+----------------------------------------------------------+-------+
| performance_schema | ON |
| performance_schema_accounts_size | -1 |
| performance_schema_digests_size | 10000 |
| performance_schema_events_stages_history_long_size | 10000 |
| performance_schema_events_stages_history_size | 10 |
| performance_schema_events_statements_history_long_size | 10000 |
| performance_schema_events_statements_history_size | 10 |
| performance_schema_events_transactions_history_long_size | 10000 |
| performance_schema_events_transactions_history_size | 10 |
| performance_schema_events_waits_history_long_size | 10000 |
| performance_schema_events_waits_history_size | 10 |
| performance_schema_hosts_size | -1 |
| performance_schema_max_cond_classes | 80 |
| performance_schema_max_cond_instances | -1 |
| performance_schema_max_digest_length | 1024 |
| performance_schema_max_file_classes | 50 |
| performance_schema_max_file_handles | 32768 |
| performance_schema_max_file_instances | -1 |
| performance_schema_max_index_stat | -1 |
| performance_schema_max_memory_classes | 320 |
| performance_schema_max_metadata_locks | -1 |
| performance_schema_max_mutex_classes | 200 |
| performance_schema_max_mutex_instances | -1 |
| performance_schema_max_prepared_statements_instances | -1 |
| performance_schema_max_program_instances | -1 |
| performance_schema_max_rwlock_classes | 40 |
| performance_schema_max_rwlock_instances | -1 |
| performance_schema_max_socket_classes | 10 |
| performance_schema_max_socket_instances | -1 |
| performance_schema_max_sql_text_length | 1024 |
| performance_schema_max_stage_classes | 150 |
| performance_schema_max_statement_classes | 192 |
| performance_schema_max_statement_stack | 10 |
| performance_schema_max_table_handles | -1 |
| performance_schema_max_table_instances | -1 |
| performance_schema_max_table_lock_stat | -1 |
| performance_schema_max_thread_classes | 50 |
| performance_schema_max_thread_instances | -1 |
| performance_schema_session_connect_attrs_size | 512 |
| performance_schema_setup_actors_size | -1 |
| performance_schema_setup_objects_size | -1 |
| performance_schema_users_size | -1 |
+----------------------------------------------------------+-------+Performance Schema system variables can be set at server startup on the command line or in option files, and many can be set at runtime. See *note performance-schema-option-variable-reference::.
The Performance Schema automatically sizes the values of several of its parameters at server startup if they are not set explicitly. For more information, see *note performance-schema-startup-configuration::.
Performance Schema system variables have the following meanings:
'performance_schema'
Command-Line Format
'--performance-schema[={OFF|ON}]'
System Variable
'performance_schema'
Scope
Global
Dynamic
No
Type
Boolean
Default Value
'ON'
The value of this variable is 'ON' or 'OFF' to indicate whether the Performance Schema is enabled. By default, the value is 'ON'. At server startup, you can specify this variable with no value or a value of 'ON' or 1 to enable it, or with a value of 'OFF' or 0 to disable it.
Even when the Performance Schema is disabled, it continues to populate the note 'global_variables': performance-schema-system-variable-tables, note 'session_variables': performance-schema-system-variable-tables, note 'global_status': performance-schema-status-variable-tables, and note 'session_status': performance-schema-status-variable-tables. tables. This occurs as necessary to permit the results for the note 'SHOW VARIABLES': show-variables. and note 'SHOW STATUS': show-status. statements to be drawn from those tables, depending on the setting of the 'show_compatibiliy_56' system variable.
'performance_schema_accounts_size'
Command-Line Format
'--performance-schema-accounts-size=#'
System Variable
'performance_schema_accounts_size'
Scope
Global
Dynamic
No
Type
Integer
Default Value
'-1' (signifies autoscaling; do not assign this literal value)
Minimum Value
'-1' (signifies autoscaling; do not assign this literal value)
Maximum Value
'1048576'
The number of rows in the note 'accounts': performance-schema-accounts-table. table. If this variable is 0, the Performance Schema does not maintain connection statistics in the note 'accounts': performance-schema-accounts-table. table or status variable information in the *note 'status_by_account': performance-schema-status-variable-summary-tables. table.
'performance_schema_digests_size'
Command-Line Format
'--performance-schema-digests-size=#'
System Variable
'performance_schema_digests_size'
Scope
Global
Dynamic
No
Type
Integer
Default Value
'-1' (signifies autosizing; do not assign this literal value)
Minimum Value
'-1' (signifies autoscaling; do not assign this literal value)
Maximum Value
'1048576'
The maximum number of rows in the *note 'events_statements_summary_by_digest': performance-schema-statement-summary-tables. table. If this maximum is exceeded such that a digest cannot be instrumented, the Performance Schema increments the 'Performance_schema_digest_lost' status variable.
For more information about statement digesting, see *note performance-schema-statement-digests::.
'performance_schema_events_stages_history_long_size'
Command-Line Format
'--performance-schema-events-stages-history-long-size=#'
System Variable
'performance_schema_events_stages_history_long_size'
Scope
Global
Dynamic
No
Type
Integer
Default Value
'-1' (signifies autosizing; do not assign this literal value)
Minimum Value
'-1' (signifies autoscaling; do not assign this literal value)
Maximum Value
'1048576'
The number of rows in the *note 'events_stages_history_long': performance-schema-events-stages-history-long-table. table.
'performance_schema_events_stages_history_size'
Command-Line Format
'--performance-schema-events-stages-history-size=#'
System Variable
'performance_schema_events_stages_history_size'
Scope
Global
Dynamic
No
Type
Integer
Default Value
'-1' (signifies autosizing; do not assign this literal value)
Minimum Value
'-1' (signifies autoscaling; do not assign this literal value)
Maximum Value
'1024'
The number of rows per thread in the *note 'events_stages_history': performance-schema-events-stages-history-table. table.
'performance_schema_events_statements_history_long_size'
Command-Line Format
'--performance-schema-events-statements-history-long-size=#'
System Variable
'performance_schema_events_statements_history_long_size'
Scope
Global
Dynamic
No
Type
Integer
Default Value
'-1' (signifies autosizing; do not assign this literal value)
Minimum Value
'-1' (signifies autoscaling; do not assign this literal value)
Maximum Value
'1048576'
The number of rows in the *note 'events_statements_history_long': performance-schema-events-statements-history-long-table. table.
'performance_schema_events_statements_history_size'
Command-Line Format
'--performance-schema-events-statements-history-size=#'
System Variable
'performance_schema_events_statements_history_size'
Scope
Global
Dynamic
No
Type
Integer
Default Value
'-1' (signifies autosizing; do not assign this literal value)
Minimum Value
'-1' (signifies autoscaling; do not assign this literal value)
Maximum Value
'1024'
The number of rows per thread in the *note 'events_statements_history': performance-schema-events-statements-history-table. table.
'performance_schema_events_transactions_history_long_size'
Command-Line Format
'--performance-schema-events-transactions-history-long-size=#'
System Variable
'performance_schema_events_transactions_history_long_size'
Scope
Global
Dynamic
No
Type
Integer
Default Value
'-1' (signifies autosizing; do not assign this literal value)
Minimum Value
'-1' (signifies autoscaling; do not assign this literal value)
Maximum Value
'1048576'
The number of rows in the *note 'events_transactions_history_long': performance-schema-events-transactions-history-long-table. table.
'performance_schema_events_transactions_history_size'
Command-Line Format
'--performance-schema-events-transactions-history-size=#'
System Variable
'performance_schema_events_transactions_history_size'
Scope
Global
Dynamic
No
Type
Integer
Default Value
'-1' (signifies autosizing; do not assign this literal value)
Minimum Value
'-1' (signifies autoscaling; do not assign this literal value)
Maximum Value
'1024'
The number of rows per thread in the *note 'events_transactions_history': performance-schema-events-transactions-history-table. table.
'performance_schema_events_waits_history_long_size'
Command-Line Format
'--performance-schema-events-waits-history-long-size=#'
System Variable
'performance_schema_events_waits_history_long_size'
Scope
Global
Dynamic
No
Type
Integer
Default Value
'-1' (signifies autosizing; do not assign this literal value)
Minimum Value
'-1' (signifies autoscaling; do not assign this literal value)
Maximum Value
'1048576'
The number of rows in the *note 'events_waits_history_long': performance-schema-events-waits-history-long-table. table.
'performance_schema_events_waits_history_size'
Command-Line Format
'--performance-schema-events-waits-history-size=#'
System Variable
'performance_schema_events_waits_history_size'
Scope
Global
Dynamic
No
Type
Integer
Default Value
'-1' (signifies autosizing; do not assign this literal value)
Minimum Value
'-1' (signifies autoscaling; do not assign this literal value)
Maximum Value
'1024'
The number of rows per thread in the *note 'events_waits_history': performance-schema-events-waits-history-table. table.
'performance_schema_hosts_size'
Command-Line Format
'--performance-schema-hosts-size=#'
System Variable
'performance_schema_hosts_size'
Scope
Global
Dynamic
No
Type
Integer
Default Value
'-1' (signifies autoscaling; do not assign this literal value)
Minimum Value
'-1' (signifies autoscaling; do not assign this literal value)
Maximum Value
'1048576'
The number of rows in the note 'hosts': performance-schema-hosts-table. table. If this variable is 0, the Performance Schema does not maintain connection statistics in the note 'hosts': performance-schema-hosts-table. table or status variable information in the *note 'status_by_host': performance-schema-status-variable-summary-tables. table.
'performance_schema_max_cond_classes'
Command-Line Format
'--performance-schema-max-cond-classes=#'
System Variable
'performance_schema_max_cond_classes'
Scope
Global
Dynamic
No
Type
Integer
Default Value
'80'
Minimum Value
'0'
Maximum Value
'256'
The maximum number of condition instruments. For information about how to set and use this variable, see *note performance-schema-status-monitoring::.
'performance_schema_max_cond_instances'
Command-Line Format
'--performance-schema-max-cond-instances=#'
System Variable
'performance_schema_max_cond_instances'
Scope
Global
Dynamic
No
Type
Integer
Default Value
'-1' (signifies autoscaling; do not assign this literal value)
Minimum Value
'-1' (signifies autoscaling; do not assign this literal value)
Maximum Value
'1048576'
The maximum number of instrumented condition objects. For information about how to set and use this variable, see *note performance-schema-status-monitoring::.
'performance_schema_max_digest_length'
Command-Line Format
'--performance-schema-max-digest-length=#'
System Variable
'performance_schema_max_digest_length'
Scope
Global
Dynamic
No
Type
Integer
Default Value
'1024'
Minimum Value
'0'
Maximum Value
'1048576'
Unit
bytes
The maximum number of bytes of memory reserved per statement for computation of normalized statement digest values in the Performance Schema. This variable is related to 'max_digest_length'; see the description of that variable in *note server-system-variables::.
For more information about statement digesting, including considerations regarding memory use, see *note performance-schema-statement-digests::.
'performance_schema_max_file_classes'
Command-Line Format
'--performance-schema-max-file-classes=#'
System Variable
'performance_schema_max_file_classes'
Scope
Global
Dynamic
No
Type
Integer
Default Value
'80'
Minimum Value
'0'
Maximum Value
'256'
The maximum number of file instruments. For information about how to set and use this variable, see *note performance-schema-status-monitoring::.
'performance_schema_max_file_handles'
Command-Line Format
'--performance-schema-max-file-handles=#'
System Variable
'performance_schema_max_file_handles'
Scope
Global
Dynamic
No
Type
Integer
Default Value
'32768'
Minimum Value
'0'
Maximum Value
'1048576'
The maximum number of opened file objects. For information about how to set and use this variable, see *note performance-schema-status-monitoring::.
The value of 'performance_schema_max_file_handles' should be greater than the value of 'open_files_limit': 'open_files_limit' affects the maximum number of open file handles the server can support and 'performance_schema_max_file_handles' affects how many of these file handles can be instrumented.
'performance_schema_max_file_instances'
Command-Line Format
'--performance-schema-max-file-instances=#'
System Variable
'performance_schema_max_file_instances'
Scope
Global
Dynamic
No
Type
Integer
Default Value
'-1' (signifies autoscaling; do not assign this literal value)
Minimum Value
'-1' (signifies autoscaling; do not assign this literal value)
Maximum Value
'1048576'
The maximum number of instrumented file objects. For information about how to set and use this variable, see *note performance-schema-status-monitoring::.
'performance_schema_max_index_stat'
Command-Line Format
'--performance-schema-max-index-stat=#'
System Variable
'performance_schema_max_index_stat'
Scope
Global
Dynamic
No
Type
Integer
Default Value
'-1' (signifies autosizing; do not assign this literal value)
Minimum Value
'-1' (signifies autoscaling; do not assign this literal value)
Maximum Value
'1048576'
The maximum number of indexes for which the Performance Schema maintains statistics. If this maximum is exceeded such that index statistics are lost, the Performance Schema increments the 'Performance_schema_index_stat_lost' status variable. The default value is autosized using the value of 'performance_schema_max_table_instances'.
'performance_schema_max_memory_classes'
Command-Line Format
'--performance-schema-max-memory-classes=#'
System Variable
'performance_schema_max_memory_classes'
Scope
Global
Dynamic
No
Type
Integer
Default Value
'320'
Minimum Value
'0'
Maximum Value
'1024'
The maximum number of memory instruments. For information about how to set and use this variable, see *note performance-schema-status-monitoring::.
'performance_schema_max_metadata_locks'
Command-Line Format
'--performance-schema-max-metadata-locks=#'
System Variable
'performance_schema_max_metadata_locks'
Scope
Global
Dynamic
No
Type
Integer
Default Value
'-1' (signifies autoscaling; do not assign this literal value)
Minimum Value
'-1' (signifies autoscaling; do not assign this literal value)
Maximum Value
'10485760'
The maximum number of metadata lock instruments. This value controls the size of the *note 'metadata_locks': performance-schema-metadata-locks-table. table. If this maximum is exceeded such that a metadata lock cannot be instrumented, the Performance Schema increments the 'Performance_schema_metadata_lock_lost' status variable.
'performance_schema_max_mutex_classes'
Command-Line Format
'--performance-schema-max-mutex-classes=#'
System Variable
'performance_schema_max_mutex_classes'
Scope
Global
Dynamic
No
Type
Integer
Default Value
'200'
Minimum Value
'0'
Maximum Value
'256'
The maximum number of mutex instruments. For information about how to set and use this variable, see *note performance-schema-status-monitoring::.
'performance_schema_max_mutex_instances'
Command-Line Format
'--performance-schema-max-mutex-instances=#'
System Variable
'performance_schema_max_mutex_instances'
Scope
Global
Dynamic
No
Type
Integer
Default Value
'-1' (signifies autoscaling; do not assign this literal value)
Minimum Value
'-1' (signifies autoscaling; do not assign this literal value)
Maximum Value
'104857600'
The maximum number of instrumented mutex objects. For information about how to set and use this variable, see *note performance-schema-status-monitoring::.
'performance_schema_max_prepared_statements_instances'
Command-Line Format
'--performance-schema-max-prepared-statements-instances=#'
System Variable
'performance_schema_max_prepared_statements_instances'
Scope
Global
Dynamic
No
Type
Integer
Default Value
'-1' (signifies autoscaling; do not assign this literal value)
Minimum Value
'-1' (signifies autoscaling; do not assign this literal value)
Maximum Value
'4194304'
The maximum number of rows in the note 'prepared_statements_instances': performance-schema-prepared-statements-instances-table. table. If this maximum is exceeded such that a prepared statement cannot be instrumented, the Performance Schema increments the 'Performance_schema_prepared_statements_lost' status variable. For information about how to set and use this variable, see note performance-schema-status-monitoring::.
The default value of this variable is autosized based on the value of the 'max_prepared_stmt_count' system variable.
'performance_schema_max_rwlock_classes'
Command-Line Format
'--performance-schema-max-rwlock-classes=#'
System Variable
'performance_schema_max_rwlock_classes'
Scope
Global
Dynamic
No
Type
Integer
Default Value (≥ 5.7.25)
'50'
Default Value (<= 5.7.24)
'40'
Minimum Value
'0'
Maximum Value
'256'
The maximum number of rwlock instruments. For information about how to set and use this variable, see *note performance-schema-status-monitoring::.
'performance_schema_max_program_instances'
Command-Line Format
'--performance-schema-max-program-instances=#'
System Variable
'performance_schema_max_program_instances'
Scope
Global
Dynamic
No
Type
Integer
Default Value
'-1' (signifies autoscaling; do not assign this literal value)
Minimum Value
'-1' (signifies autoscaling; do not assign this literal value)
Maximum Value
'1048576'
The maximum number of stored programs for which the Performance Schema maintains statistics. If this maximum is exceeded, the Performance Schema increments the 'Performance_schema_program_lost' status variable. For information about how to set and use this variable, see *note performance-schema-status-monitoring::.
'performance_schema_max_rwlock_instances'
Command-Line Format
'--performance-schema-max-rwlock-instances=#'
System Variable
'performance_schema_max_rwlock_instances'
Scope
Global
Dynamic
No
Type
Integer
Default Value
'-1' (signifies autosizing; do not assign this literal value)
Minimum Value
'-1' (signifies autosizing; do not assign this literal value)
Maximum Value
'104857600'
The maximum number of instrumented rwlock objects. For information about how to set and use this variable, see *note performance-schema-status-monitoring::.
'performance_schema_max_socket_classes'
Command-Line Format
'--performance-schema-max-socket-classes=#'
System Variable
'performance_schema_max_socket_classes'
Scope
Global
Dynamic
No
Type
Integer
Default Value
'10'
Minimum Value
'0'
Maximum Value
'256'
The maximum number of socket instruments. For information about how to set and use this variable, see *note performance-schema-status-monitoring::.
'performance_schema_max_socket_instances'
Command-Line Format
'--performance-schema-max-socket-instances=#'
System Variable
'performance_schema_max_socket_instances'
Scope
Global
Dynamic
No
Type
Integer
Default Value
'-1' (signifies autoscaling; do not assign this literal value)
Minimum Value
'-1' (signifies autoscaling; do not assign this literal value)
Maximum Value
'1048576'
The maximum number of instrumented socket objects. For information about how to set and use this variable, see *note performance-schema-status-monitoring::.
'performance_schema_max_sql_text_length'
Command-Line Format
'--performance-schema-max-sql-text-length=#'
System Variable
'performance_schema_max_sql_text_length'
Scope
Global
Dynamic
No
Type
Integer
Default Value
'1024'
Minimum Value
'0'
Maximum Value
'1048576'
Unit
bytes
The maximum number of bytes used to store SQL statements in the 'SQL_TEXT' column of the note 'events_statements_current': performance-schema-events-statements-current-table, note 'events_statements_history': performance-schema-events-statements-history-table, and *note 'events_statements_history_long': performance-schema-events-statements-history-long-table. statement event tables. Any bytes in excess of 'performance_schema_max_sql_text_length' are discarded and do not appear in the 'SQL_TEXT' column. Statements differing only after that many initial bytes are indistinguishable in this column.
Decreasing the 'performance_schema_max_sql_text_length' value reduces memory use but causes more statements to become indistinguishable if they differ only at the end. Increasing the value increases memory use but permits longer statements to be distinguished.
'performance_schema_max_stage_classes'
Command-Line Format
'--performance-schema-max-stage-classes=#'
System Variable
'performance_schema_max_stage_classes'
Scope
Global
Dynamic
No
Type
Integer
Default Value
'150'
Minimum Value
'0'
Maximum Value
'256'
The maximum number of stage instruments. For information about how to set and use this variable, see *note performance-schema-status-monitoring::.
'performance_schema_max_statement_classes'
Command-Line Format
'--performance-schema-max-statement-classes=#'
System Variable
'performance_schema_max_statement_classes'
Scope
Global
Dynamic
No
Type
Integer
Minimum Value
'0'
Maximum Value
'256'
The maximum number of statement instruments. For information about how to set and use this variable, see *note performance-schema-status-monitoring::.
The default value is calculated at server build time based on the number of commands in the client/server protocol and the number of SQL statement types supported by the server.
This variable should not be changed, unless to set it to 0 to disable all statement instrumentation and save all memory associated with it. Setting the variable to nonzero values other than the default has no benefit; in particular, values larger than the default cause more memory to be allocated then is needed.
'performance_schema_max_statement_stack'
Command-Line Format
'--performance-schema-max-statement-stack=#'
System Variable
'performance_schema_max_statement_stack'
Scope
Global
Dynamic
No
Type
Integer
Default Value
'10'
Minimum Value
'1'
Maximum Value
'256'
The maximum depth of nested stored program calls for which the Performance Schema maintains statistics. When this maximum is exceeded, the Performance Schema increments the 'Performance_schema_nested_statement_lost' status variable for each stored program statement executed.
'performance_schema_max_table_handles'
Command-Line Format
'--performance-schema-max-table-handles=#'
System Variable
'performance_schema_max_table_handles'
Scope
Global
Dynamic
No
Type
Integer
Default Value
'-1' (signifies autoscaling; do not assign this literal value)
Minimum Value
'-1' (signifies autoscaling; do not assign this literal value)
Maximum Value
'1048576'
The maximum number of opened table objects. This value controls the size of the note 'table_handles': performance-schema-table-handles-table. table. If this maximum is exceeded such that a table handle cannot be instrumented, the Performance Schema increments the 'Performance_schema_table_handles_lost' status variable. For information about how to set and use this variable, see note performance-schema-status-monitoring::.
'performance_schema_max_table_instances'
Command-Line Format
'--performance-schema-max-table-instances=#'
System Variable
'performance_schema_max_table_instances'
Scope
Global
Dynamic
No
Type
Integer
Default Value
'-1' (signifies autoscaling; do not assign this literal value)
Minimum Value
'-1' (signifies autoscaling; do not assign this literal value)
Maximum Value
'1048576'
The maximum number of instrumented table objects. For information about how to set and use this variable, see *note performance-schema-status-monitoring::.
'performance_schema_max_table_lock_stat'
Command-Line Format
'--performance-schema-max-table-lock-stat=#'
System Variable
'performance_schema_max_table_lock_stat'
Scope
Global
Dynamic
No
Type
Integer
Default Value
'-1' (signifies autosizing; do not assign this literal value)
Minimum Value
'-1' (signifies autoscaling; do not assign this literal value)
Maximum Value
'1048576'
The maximum number of tables for which the Performance Schema maintains lock statistics. If this maximum is exceeded such that table lock statistics are lost, the Performance Schema increments the 'Performance_schema_table_lock_stat_lost' status variable.
'performance_schema_max_thread_classes'
Command-Line Format
'--performance-schema-max-thread-classes=#'
System Variable
'performance_schema_max_thread_classes'
Scope
Global
Dynamic
No
Type
Integer
Default Value
'50'
Minimum Value
'0'
Maximum Value
'256'
The maximum number of thread instruments. For information about how to set and use this variable, see *note performance-schema-status-monitoring::.
'performance_schema_max_thread_instances'
Command-Line Format
'--performance-schema-max-thread-instances=#'
System Variable
'performance_schema_max_thread_instances'
Scope
Global
Dynamic
No
Type
Integer
Default Value
'-1' (signifies autosizing; do not assign this literal value)
Minimum Value
'-1' (signifies autoscaling; do not assign this literal value)
Maximum Value
'1048576'
The maximum number of instrumented thread objects. The value controls the size of the note 'threads': performance-schema-threads-table. table. If this maximum is exceeded such that a thread cannot be instrumented, the Performance Schema increments the 'Performance_schema_thread_instances_lost' status variable. For information about how to set and use this variable, see note performance-schema-status-monitoring::.
The 'max_connections' system variable affects how many threads can run in the server. 'performance_schema_max_thread_instances' affects how many of these running threads can be instrumented.
The note 'variables_by_thread': performance-schema-system-variable-tables. and note 'status_by_thread': performance-schema-status-variable-tables. tables contain system and status variable information only about foreground threads. If not all threads are instrumented by the Performance Schema, this table may miss some rows. In this case, the 'Performance_schema_thread_instances_lost' status variable is greater than zero.
'performance_schema_session_connect_attrs_size'
Command-Line Format
'--performance-schema-session-connect-attrs-size=#'
System Variable
'performance_schema_session_connect_attrs_size'
Scope
Global
Dynamic
No
Type
Integer
Default Value
'-1' (signifies autosizing; do not assign this literal value)
Minimum Value
'-1' (signifies autosizing; do not assign this literal value)
Maximum Value
'1048576'
Unit
bytes
The amount of preallocated memory per thread reserved to hold connection attribute key-value pairs. If the aggregate size of connection attribute data sent by a client is larger than this amount, the Performance Schema truncates the attribute data, increments the 'Performance_schema_session_connect_attrs_lost' status variable, and writes a message to the error log indicating that truncation occurred if the 'log_error_verbosity' system variable value is greater than 1.
The default value of 'performance_schema_session_connect_attrs_size' is autosized at server startup. This value may be small, so if truncation occurs ('Performance_schema_session_connect_attrs_lost' becomes nonzero), you may wish to set 'performance_schema_session_connect_attrs_size' explicitly to a larger value.
Although the maximum permitted 'performance_schema_session_connect_attrs_size' value is 1MB, the effective maximum is 64KB because the server imposes a limit of 64KB on the aggregate size of connection attribute data it can accept. If a client attempts to send more than 64KB of attribute data, the server rejects the connection. For more information, see *note performance-schema-connection-attribute-tables::.
'performance_schema_setup_actors_size'
Command-Line Format
'--performance-schema-setup-actors-size=#'
System Variable
'performance_schema_setup_actors_size'
Scope
Global
Dynamic
No
Type
Integer
Default Value
'-1' (signifies autoscaling; do not assign this literal value)
Minimum Value
'-1' (signifies autosizing; do not assign this literal value)
Maximum Value
'1048576'
The number of rows in the *note 'setup_actors': performance-schema-setup-actors-table. table.
'performance_schema_setup_objects_size'
Command-Line Format
'--performance-schema-setup-objects-size=#'
System Variable
'performance_schema_setup_objects_size'
Scope
Global
Dynamic
No
Type
Integer
Default Value
'-1' (signifies autoscaling; do not assign this literal value)
Minimum Value
'-1' (signifies autoscaling; do not assign this literal value)
Maximum Value
'1048576'
The number of rows in the *note 'setup_objects': performance-schema-setup-objects-table. table.
'performance_schema_show_processlist'
Command-Line Format
'--performance-schema-show-processlist[={OFF|ON}]'
Introduced
5.7.39
System Variable
'performance_schema_show_processlist'
Scope
Global
Dynamic
Yes
Type
Boolean
Default Value
'OFF'
The *note 'SHOW PROCESSLIST': show-processlist. statement provides process information by collecting thread data from all active threads. The 'performance_schema_show_processlist' variable determines which 'SHOW PROCESSLIST' implementation to use:
* The default implementation iterates across active threads from
within the thread manager while holding a global mutex. This
has negative performance consequences, particularly on busy
systems.
* The alternative *note 'SHOW PROCESSLIST': show-processlist.
implementation is based on the Performance Schema *note
'processlist': performance-schema-processlist-table. table.
This implementation queries active thread data from the
Performance Schema rather than the thread manager and does not
require a mutex.To enable the alternative implementation, enable the 'performance_schema_show_processlist' system variable. To ensure that the default and alternative implementations yield the same information, certain configuration requirements must be met; see *note performance-schema-processlist-table::.
'performance_schema_users_size'
Command-Line Format
'--performance-schema-users-size=#'
System Variable
'performance_schema_users_size'
Scope
Global
Dynamic
No
Type
Integer
Default Value
'-1' (signifies autoscaling; do not assign this literal value)
Minimum Value
'-1' (signifies autoscaling; do not assign this literal value)
Maximum Value
'1048576'
The number of rows in the note 'users': performance-schema-users-table. table. If this variable is 0, the Performance Schema does not maintain connection statistics in the note 'users': performance-schema-users-table. table or status variable information in the *note 'status_by_user': performance-schema-status-variable-summary-tables. table.
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