6.4.5.11 Audit Log Reference

The following sections provide a reference to MySQL Enterprise Audit elements:

• Audit Log Tables

• Audit Log Functions

• Audit Log Option and Variable Reference

• Audit Log Options and Variables

• Audit Log Status Variables

To install the audit log tables and functions, use the instructions provided in Section 6.4.5.2, “Installing or Uninstalling MySQL Enterprise Audit”. Unless those objects are installed, the audit_log plugin operates in legacy mode. See Section 6.4.5.10, “Legacy Mode Audit Log Filtering”.

Audit Log Tables

MySQL Enterprise Audit uses tables in the mysql system database for persistent storage of filter and user account data. The tables can be accessed only by users who have privileges for that database. The tables use the InnoDB storage engine (MyISAM prior to MySQL 5.7.21).

If these tables are missing, the audit_log plugin operates in legacy mode. See Section 6.4.5.10, “Legacy Mode Audit Log Filtering”.

The audit_log_filter table stores filter definitions. The table has these columns:

• NAME

  The filter name.

• FILTER

  The filter definition associated with the filter name. Definitions are stored as JSON values.

The audit_log_user table stores user account information. The table has these columns:

• USER

  The user name part of an account. For an account user1@localhost, the USER part is user1.

• HOST

  The host name part of an account. For an account user1@localhost, the HOST part is localhost.

• FILTERNAME

  The name of the filter assigned to the account. The filter name associates the account with a filter defined in the audit_log_filter table.

Audit Log Functions

This section describes, for each audit log function, its purpose, calling sequence, and return value. For information about the conditions under which these functions can be invoked, see Section 6.4.5.7, “Audit Log Filtering”.

Each audit log function returns a string that indicates whether the operation succeeded. OK indicates success. ERROR: message indicates failure.

Audit log functions treat string arguments as binary strings (which means they do not distinguish lettercase), and string return values are binary strings.

If an audit log function is invoked from within the mysql client, binary string results display using hexadecimal notation, depending on the value of the --binary-as-hex. For more information about that option, see Section 4.5.1, “mysql — The MySQL Command-Line Client”.

These audit log functions are available:

• audit_log_encryption_password_get()

  Retrieves the current audit log encryption password as a binary string. The password is fetched from the MySQL keyring, which must be enabled or an error occurs. Any keyring plugin can be used; for instructions, see Section 6.4.4, “The MySQL Keyring”.

  For additional information about audit log encryption, see Encrypting Audit Log Files.

  Arguments:

  None.

  Return value:

  The password string for success (up to 766 bytes), or NULL and an error for failure.

  Example:

  mysql> SELECT audit_log_encryption_password_get();
  +-------------------------------------+
  | audit_log_encryption_password_get() |
  +-------------------------------------+
  | secret                              |
  +-------------------------------------+

• audit_log_encryption_password_set(password)

  Sets the audit log encryption password to the argument, stores the password in the MySQL keyring. If encryption is enabled, the function performs a log file rotation operation that renames the current log file, and begins a new log file encrypted with the password. The keyring must be enabled or an error occurs. Any keyring plugin can be used; for instructions, see Section 6.4.4, “The MySQL Keyring”.

  For additional information about audit log encryption, see Encrypting Audit Log Files.

  Arguments:

  password: The password string. The maximum permitted length is 766 bytes.

  Return value:

  1 for success, 0 for failure.

  Example:

  mysql> SELECT audit_log_encryption_password_set(password);
  +---------------------------------------------+
  | audit_log_encryption_password_set(password) |
  +---------------------------------------------+
  | 1                                           |
  +---------------------------------------------+

• audit_log_filter_flush()

  Calling any of the other filtering functions affects operational audit log filtering immediately and updates the audit log tables. If instead you modify the contents of those tables directly using statements such as INSERT, UPDATE, and DELETE, the changes do not affect filtering immediately. To flush your changes and make them operational, call audit_log_filter_flush().

  Warning

  audit_log_filter_flush() should be used only after modifying the audit tables directly, to force reloading all filters. Otherwise, this function should be avoided. It is, in effect, a simplified version of unloading and reloading the audit_log plugin with UNINSTALL PLUGIN plus INSTALL PLUGIN.

  audit_log_filter_flush() affects all current sessions and detaches them from their previous filters. Current sessions are no longer logged unless they disconnect and reconnect, or execute a change-user operation.

  If this function fails, an error message is returned and the audit log is disabled until the next successful call to audit_log_filter_flush().

  Arguments:

  None.

  Return value:

  A string that indicates whether the operation succeeded. OK indicates success. ERROR: message indicates failure.

  Example:

  mysql> SELECT audit_log_filter_flush();
  +--------------------------+
  | audit_log_filter_flush() |
  +--------------------------+
  | OK                       |
  +--------------------------+

• audit_log_filter_remove_filter(filter_name)

  Given a filter name, removes the filter from the current set of filters. It is not an error for the filter not to exist.

  If a removed filter is assigned to any user accounts, those users stop being filtered (they are removed from the audit_log_user table). Termination of filtering includes any current sessions for those users: They are detached from the filter and no longer logged.

  Arguments:

  • filter_name: A string that specifies the filter name.

  Return value:

  A string that indicates whether the operation succeeded. OK indicates success. ERROR: message indicates failure.

  Example:

  mysql> SELECT audit_log_filter_remove_filter('SomeFilter');
  +----------------------------------------------+
  | audit_log_filter_remove_filter('SomeFilter') |
  +----------------------------------------------+
  | OK                                           |
  +----------------------------------------------+

• audit_log_filter_remove_user(user_name)

  Given a user account name, cause the user to be no longer assigned to a filter. It is not an error if the user has no filter assigned. Filtering of current sessions for the user remains unaffected. New connections for the user are filtered using the default account filter if there is one, and are not logged otherwise.

  If the name is %, the function removes the default account filter that is used for any user account that has no explicitly assigned filter.

  Arguments:

  • user_name: The user account name as a string in user_name@host_name format, or % to represent the default account.

  Return value:

  A string that indicates whether the operation succeeded. OK indicates success. ERROR: message indicates failure.

  Example:

  mysql> SELECT audit_log_filter_remove_user('user1@localhost');
  +-------------------------------------------------+
  | audit_log_filter_remove_user('user1@localhost') |
  +-------------------------------------------------+
  | OK                                              |
  +-------------------------------------------------+

• audit_log_filter_set_filter(filter_name, definition)

  Given a filter name and definition, adds the filter to the current set of filters. If the filter already exists and is used by any current sessions, those sessions are detached from the filter and are no longer logged. This occurs because the new filter definition has a new filter ID that differs from its previous ID.

  Arguments:

  • filter_name: A string that specifies the filter name.

  • definition: A JSON value that specifies the filter definition.

  Return value:

  A string that indicates whether the operation succeeded. OK indicates success. ERROR: message indicates failure.

  Example:

  mysql> SET @f = '{ "filter": { "log": false } }';
  mysql> SELECT audit_log_filter_set_filter('SomeFilter', @f);
  +-----------------------------------------------+
  | audit_log_filter_set_filter('SomeFilter', @f) |
  +-----------------------------------------------+
  | OK                                            |
  +-----------------------------------------------+

• audit_log_filter_set_user(user_name, filter_name)

  Given a user account name and a filter name, assigns the filter to the user. A user can be assigned only one filter, so if the user was already assigned a filter, the assignment is replaced. Filtering of current sessions for the user remains unaffected. New connections are filtered using the new filter.

  As a special case, the name % represents the default account. The filter is used for connections from any user account that has no explicitly assigned filter.

  Arguments:

  • user_name: The user account name as a string in user_name@host_name format, or % to represent the default account.

  • filter_name: A string that specifies the filter name.

  Return value:

  A string that indicates whether the operation succeeded. OK indicates success. ERROR: message indicates failure.

  Example:

  mysql> SELECT audit_log_filter_set_user('user1@localhost', 'SomeFilter');
  +------------------------------------------------------------+
  | audit_log_filter_set_user('user1@localhost', 'SomeFilter') |
  +------------------------------------------------------------+
  | OK                                                         |
  +------------------------------------------------------------+

• audit_log_read([arg])

  Reads the audit log and returns a binary JSON string result. If the audit log format is not JSON, an error occurs.

  With no argument or a JSON hash argument, audit_log_read() reads events from the audit log and returns a JSON string containing an array of audit events. Items in the hash argument influence how reading occurs, as described later. Each element in the returned array is an event represented as a JSON hash, with the exception that the last element may be a JSON null value to indicate no following events are available to read.

  With an argument consisting of a JSON null value, audit_log_read() closes the current read sequence.

  For additional details about the audit log-reading process, see Section 6.4.5.6, “Reading Audit Log Files”.

  Arguments:

  arg: The argument is optional. If omitted, the function reads events from the current position. If present, the argument can be a JSON null value to close the read sequence, or a JSON hash. Within a hash argument, items are optional and control aspects of the read operation such as the position at which to begin reading or how many events to read. The following items are significant (other items are ignored):

  • timestamp, id: The position within the audit log of the first event to read. If the position is omitted from the argument, reading continues from the current position. The timestamp and id items together comprise a bookmark that uniquely identify a particular event. If an audit_log_read() argument includes either item, it must include both to completely specify a position or an error occurs.

    To obtain a bookmark for the most recently written event, call audit_log_read_bookmark().

  • max_array_length: The maximum number of events to read from the log. If this item is omitted, the default is to read to the end of the log or until the read buffer is full, whichever comes first.

  Return value:

  If the call succeeds, the return value is a binary JSON string containing an array of audit events, or a JSON null value if that was passed as the argument to close the read sequence. If the call fails, the return value is NULL and an error occurs.

  Example:

  mysql> SELECT audit_log_read(audit_log_read_bookmark());
  +-----------------------------------------------------------------------+
  | audit_log_read(audit_log_read_bookmark())                             |
  +-----------------------------------------------------------------------+
  | [ {"timestamp":"2020-05-18 22:41:24","id":0,"class":"connection", ... |
  +-----------------------------------------------------------------------+
  mysql> SELECT audit_log_read('null');
  +------------------------+
  | audit_log_read('null') |
  +------------------------+
  | null                   |
  +------------------------+

• audit_log_read_bookmark()

  Returns a binary JSON string representing a bookmark for the most recently written audit log event. If the audit log format is not JSON, an error occurs.

  The bookmark is a JSON hash with timestamp and id items that uniquely identify the position of an event within the audit log. It is suitable for passing to audit_log_read() to indicate to that function the position at which to begin reading.

  For additional details about the audit log-reading process, see Section 6.4.5.6, “Reading Audit Log Files”.

  Arguments:

  None.

  Return value:

  A binary JSON string containing a bookmark for success, or NULL and an error for failure.

  Example:

  mysql> SELECT audit_log_read_bookmark();
  +-------------------------------------------------+
  | audit_log_read_bookmark()                       |
  +-------------------------------------------------+
  | { "timestamp": "2019-10-03 21:03:44", "id": 0 } |
  +-------------------------------------------------+

Audit Log Option and Variable Reference

Table 6.34 Audit Log Option and Variable Reference

Name	Cmd-Line	Option File	System Var	Status Var	Var Scope	Dynamic
audit-log	Yes	Yes
audit_log_buffer_size	Yes	Yes	Yes		Global	No
audit_log_compression	Yes	Yes	Yes		Global	No
audit_log_connection_policy	Yes	Yes	Yes		Global	Yes
audit_log_current_session			Yes		Both	No
Audit_log_current_size				Yes	Global	No
audit_log_disable	Yes	Yes	Yes		Global	Yes
audit_log_encryption	Yes	Yes	Yes		Global	No
Audit_log_event_max_drop_size				Yes	Global	No
Audit_log_events				Yes	Global	No
Audit_log_events_filtered				Yes	Global	No
Audit_log_events_lost				Yes	Global	No
Audit_log_events_written				Yes	Global	No
audit_log_exclude_accounts	Yes	Yes	Yes		Global	Yes
audit_log_file	Yes	Yes	Yes		Global	No
audit_log_filter_id			Yes		Both	No
audit_log_flush			Yes		Global	Yes
audit_log_format	Yes	Yes	Yes		Global	No
audit_log_include_accounts	Yes	Yes	Yes		Global	Yes
audit_log_policy	Yes	Yes	Yes		Global	No
audit_log_read_buffer_size	Yes	Yes	Yes		Varies	Varies
audit_log_rotate_on_size	Yes	Yes	Yes		Global	Yes
audit_log_statement_policy	Yes	Yes	Yes		Global	Yes
audit_log_strategy	Yes	Yes	Yes		Global	No
Audit_log_total_size				Yes	Global	No
Audit_log_write_waits				Yes	Global	No

Audit Log Options and Variables

This section describes the command options and system variables that configure operation of MySQL Enterprise Audit. If values specified at startup time are incorrect, the audit_log plugin may fail to initialize properly and the server does not load it. In this case, the server may also produce error messages for other audit log settings because it does not recognize them.

To configure activation of the audit log plugin, use this option:

• --audit-log[=value]

  Command-Line Format	--audit-log[=value]
  Type	Enumeration
  Default Value	ON
  Valid Values	ON OFF FORCE FORCE_PLUS_PERMANENT

  This option controls how the server loads the audit_log plugin at startup. It is available only if the plugin has been previously registered with INSTALL PLUGIN or is loaded with --plugin-load or --plugin-load-add. See Section 6.4.5.2, “Installing or Uninstalling MySQL Enterprise Audit”.

  The option value should be one of those available for plugin-loading options, as described in Section 5.5.1, “Installing and Uninstalling Plugins”. For example, --audit-log=FORCE_PLUS_PERMANENT tells the server to load the plugin and prevent it from being removed while the server is running.

If the audit log plugin is enabled, it exposes several system variables that permit control over logging:

mysql> SHOW VARIABLES LIKE 'audit_log%';
+--------------------------------------+--------------+
| Variable_name                        | Value        |
+--------------------------------------+--------------+
| audit_log_buffer_size                | 1048576      |
| audit_log_compression                | NONE         |
| audit_log_connection_policy          | ALL          |
| audit_log_current_session            | OFF          |
| audit_log_disable                    | OFF          |
| audit_log_encryption                 | NONE         |
| audit_log_exclude_accounts           |              |
| audit_log_file                       | audit.log    |
| audit_log_filter_id                  | 0            |
| audit_log_flush                      | OFF          |
| audit_log_format                     | NEW          |
| audit_log_format_unix_timestamp      | OFF          |
| audit_log_include_accounts           |              |
| audit_log_policy                     | ALL          |
| audit_log_read_buffer_size           | 32768        |
| audit_log_rotate_on_size             | 0            |
| audit_log_statement_policy           | ALL          |
| audit_log_strategy                   | ASYNCHRONOUS |
+--------------------------------------+--------------+

You can set any of these variables at server startup, and some of them at runtime. Those that are available only for legacy mode audit log filtering are so noted.

• audit_log_buffer_size

  Command-Line Format	--audit-log-buffer-size=#
  System Variable	audit_log_buffer_size
  Scope	Global
  Dynamic	No
  Type	Integer
  Default Value	1048576
  Minimum Value	4096
  Maximum Value (64-bit platforms)	18446744073709547520
  Maximum Value (32-bit platforms)	4294967295
  Unit	bytes
  Block Size	4096

  When the audit log plugin writes events to the log asynchronously, it uses a buffer to store event contents prior to writing them. This variable controls the size of that buffer, in bytes. The server adjusts the value to a multiple of 4096. The plugin uses a single buffer, which it allocates when it initializes and removes when it terminates. The plugin allocates this buffer only if logging is asynchronous.

• audit_log_compression

  Command-Line Format	--audit-log-compression=value
  Introduced	5.7.21
  System Variable	audit_log_compression
  Scope	Global
  Dynamic	No
  Type	Enumeration
  Default Value	NONE
  Valid Values	NONE GZIP

  The type of compression for the audit log file. Permitted values are NONE (no compression; the default) and GZIP (GNU Zip compression). For more information, see Compressing Audit Log Files.

• audit_log_connection_policy

  Command-Line Format	--audit-log-connection-policy=value
  System Variable	audit_log_connection_policy
  Scope	Global
  Dynamic	Yes
  Type	Enumeration
  Default Value	ALL
  Valid Values	ALL ERRORS NONE

  Note

  This variable applies only to legacy mode audit log filtering (see Section 6.4.5.10, “Legacy Mode Audit Log Filtering”).

  The policy controlling how the audit log plugin writes connection events to its log file. The following table shows the permitted values.

  Value	Description
  ALL	Log all connection events
  ERRORS	Log only failed connection events
  NONE	Do not log connection events

  Note

  At server startup, any explicit value given for audit_log_connection_policy may be overridden if audit_log_policy is also specified, as described in Section 6.4.5.5, “Configuring Audit Logging Characteristics”.

• audit_log_current_session

  System Variable	audit_log_current_session
  Scope	Global, Session
  Dynamic	No
  Type	Boolean
  Default Value	depends on filtering policy

  Whether audit logging is enabled for the current session. The session value of this variable is read only. It is set when the session begins based on the values of the audit_log_include_accounts and audit_log_exclude_accounts system variables. The audit log plugin uses the session value to determine whether to audit events for the session. (There is a global value, but the plugin does not use it.)

• audit_log_disable

  Command-Line Format	--audit-log-disable[={OFF|ON}]
  Introduced	5.7.37
  System Variable	audit_log_disable
  Scope	Global
  Dynamic	Yes
  Type	Boolean
  Default Value	OFF

  Permits disabling audit logging for all connecting and connected sessions. Disabling audit logging requires the SUPER privilege. See Section 6.4.5.9, “Disabling Audit Logging”.

• audit_log_encryption

  Command-Line Format	--audit-log-encryption=value
  Introduced	5.7.21
  System Variable	audit_log_encryption
  Scope	Global
  Dynamic	No
  Type	Enumeration
  Default Value	NONE
  Valid Values	NONE AES

  The type of encryption for the audit log file. Permitted values are NONE (no encryption; the default) and AES (AES-256-CBC cipher encryption). For more information, see Encrypting Audit Log Files.

• audit_log_exclude_accounts

  Command-Line Format	--audit-log-exclude-accounts=value
  System Variable	audit_log_exclude_accounts
  Scope	Global
  Dynamic	Yes
  Type	String
  Default Value	NULL

  Note

  This variable applies only to legacy mode audit log filtering (see Section 6.4.5.10, “Legacy Mode Audit Log Filtering”).

  The accounts for which events should not be logged. The value should be NULL or a string containing a list of one or more comma-separated account names. For more information, see Section 6.4.5.7, “Audit Log Filtering”.

  Modifications to audit_log_exclude_accounts affect only connections created subsequent to the modification, not existing connections.

• audit_log_file

  Command-Line Format	--audit-log-file=file_name
  System Variable	audit_log_file
  Scope	Global
  Dynamic	No
  Type	File name
  Default Value	audit.log

  The base name and suffix of the file to which the audit log plugin writes events. The default value is audit.log, regardless of logging format. To have the name suffix correspond to the format, set the name explicitly, choosing a different suffix (for example, audit.xml for XML format, audit.json for JSON format).

  If the value of audit_log_file is a relative path name, the plugin interprets it relative to the data directory. If the value is a full path name, the plugin uses the value as is. A full path name may be useful if it is desirable to locate audit files on a separate file system or directory. For security reasons, write the audit log file to a directory accessible only to the MySQL server and to users with a legitimate reason to view the log.

  For details about how the audit log plugin interprets the audit_log_file value and the rules for file renaming that occurs at plugin initialization and termination, see Naming Conventions for Audit Log Files.

  As of MySQL 5.7.21, the audit log plugin uses the directory containing the audit log file (determined from the audit_log_file value) as the location to search for readable audit log files. From these log files and the current file, the plugin constructs a list of the ones that are subject to use with the audit log bookmarking and reading functions. See Section 6.4.5.6, “Reading Audit Log Files”.

• audit_log_filter_id

  Introduced	5.7.13
  System Variable	audit_log_filter_id
  Scope	Global, Session
  Dynamic	No
  Type	Integer
  Default Value	1
  Minimum Value	0
  Maximum Value	4294967295

  The session value of this variable indicates the internally maintained ID of the audit filter for the current session. A value of 0 means that the session has no filter assigned.

• audit_log_flush

  System Variable	audit_log_flush
  Scope	Global
  Dynamic	Yes
  Type	Boolean
  Default Value	OFF

  If audit_log_rotate_on_size is 0, automatic audit log file rotation is disabled and rotation occurs only when performed manually. In that case, enabling audit_log_flush by setting it to 1 or ON causes the audit log plugin to close and reopen its log file to flush it. (The variable value remains OFF so that you need not disable it explicitly before enabling it again to perform another flush.) For more information, see Section 6.4.5.5, “Configuring Audit Logging Characteristics”.

• audit_log_format

  Command-Line Format	--audit-log-format=value
  System Variable	audit_log_format
  Scope	Global
  Dynamic	No
  Type	Enumeration
  Default Value	NEW
  Valid Values (≥ 5.7.21)	OLD NEW JSON
  Valid Values (≤ 5.7.20)	OLD NEW

  The audit log file format. Permitted values are OLD (old-style XML), NEW (new-style XML; the default), and (as of MySQL 5.7.21) JSON. For details about each format, see Section 6.4.5.4, “Audit Log File Formats”.

  Note

  For information about issues to consider when changing the log format, see Selecting Audit Log File Format.

• audit_log_format_unix_timestamp

  Command-Line Format	--audit-log-format-unix-timestamp[={OFF|ON}]
  Introduced	5.7.35
  System Variable	audit_log_format_unix_timestamp
  Scope	Global
  Dynamic	Yes
  Type	Boolean
  Default Value	OFF

  This variable applies only for JSON-format audit log output. When that is true, enabling this variable causes each log file record to include a time field. The field value is an integer that represents the UNIX timestamp value indicating the date and time when the audit event was generated.

  Changing the value of this variable at runtime causes log file rotation so that, for a given JSON-format log file, all records in the file either do or do not include the time field.

• audit_log_include_accounts

  Command-Line Format	--audit-log-include-accounts=value
  System Variable	audit_log_include_accounts
  Scope	Global
  Dynamic	Yes
  Type	String
  Default Value	NULL

  Note

  This variable applies only to legacy mode audit log filtering (see Section 6.4.5.10, “Legacy Mode Audit Log Filtering”).

  The accounts for which events should be logged. The value should be NULL or a string containing a list of one or more comma-separated account names. For more information, see Section 6.4.5.7, “Audit Log Filtering”.

  Modifications to audit_log_include_accounts affect only connections created subsequent to the modification, not existing connections.

• audit_log_policy

  Command-Line Format	--audit-log-policy=value
  System Variable	audit_log_policy
  Scope	Global
  Dynamic	No
  Type	Enumeration
  Default Value	ALL
  Valid Values	ALL LOGINS QUERIES NONE

  Note

  This variable applies only to legacy mode audit log filtering (see Section 6.4.5.10, “Legacy Mode Audit Log Filtering”).

  The policy controlling how the audit log plugin writes events to its log file. The following table shows the permitted values.

  Value	Description
  ALL	Log all events
  LOGINS	Log only login events
  QUERIES	Log only query events
  NONE	Log nothing (disable the audit stream)

  audit_log_policy can be set only at server startup. At runtime, it is a read-only variable. Two other system variables, audit_log_connection_policy and audit_log_statement_policy, provide finer control over logging policy and can be set either at startup or at runtime. If you use audit_log_policy at startup instead of the other two variables, the server uses its value to set those variables. For more information about the policy variables and their interaction, see Section 6.4.5.5, “Configuring Audit Logging Characteristics”.

• audit_log_read_buffer_size

  Command-Line Format	--audit-log-read-buffer-size=#
  Introduced	5.7.21
  System Variable	audit_log_read_buffer_size
  Scope (≥ 5.7.23)	Global, Session
  Scope (≤ 5.7.22)	Global
  Dynamic (≥ 5.7.23)	Yes
  Dynamic (≤ 5.7.22)	No
  Type	Integer
  Default Value (≥ 5.7.23)	32768
  Default Value (≤ 5.7.22)	1048576
  Minimum Value (≥ 5.7.23)	32768
  Minimum Value (≤ 5.7.22)	1024
  Maximum Value	4194304
  Unit	bytes

  The buffer size for reading from the audit log file, in bytes. The audit_log_read() function reads no more than this many bytes. Log file reading is supported only for JSON log format. For more information, see Section 6.4.5.6, “Reading Audit Log Files”.

  As of MySQL 5.7.23, this variable has a default of 32KB and can be set at runtime. Each client should set its session value of audit_log_read_buffer_size appropriately for its use of audit_log_read(). Prior to MySQL 5.7.23, audit_log_read_buffer_size has a default of 1MB, affects all clients, and can be changed only at server startup.

• audit_log_rotate_on_size

  Command-Line Format	--audit-log-rotate-on-size=#
  System Variable	audit_log_rotate_on_size
  Scope	Global
  Dynamic	Yes
  Type	Integer
  Default Value	0
  Minimum Value	0
  Maximum Value	18446744073709551615
  Unit	bytes
  Block Size	4096

  If audit_log_rotate_on_size is 0, the audit log plugin does not perform automatic size-based log file rotation. If rotation is to occur, you must perform it manually; see Manual Audit Log File Rotation.

  If audit_log_rotate_on_size is greater than 0, automatic size-based log file rotation occurs. Whenever a write to the log file causes its size to exceed the audit_log_rotate_on_size value, the audit log plugin renames the current log file and opens a new current log file using the original name.

  If you set audit_log_rotate_on_size to a value that is not a multiple of 4096, it is truncated to the nearest multiple. In particular, setting it to a value less than 4096 sets it to 0 and no rotation occurs, except manually.

  For more information about audit log file rotation, see Space Management of Audit Log Files.

• audit_log_statement_policy

  Command-Line Format	--audit-log-statement-policy=value
  System Variable	audit_log_statement_policy
  Scope	Global
  Dynamic	Yes
  Type	Enumeration
  Default Value	ALL
  Valid Values	ALL ERRORS NONE

  Note

  This variable applies only to legacy mode audit log filtering (see Section 6.4.5.10, “Legacy Mode Audit Log Filtering”).

  The policy controlling how the audit log plugin writes statement events to its log file. The following table shows the permitted values.

  Value	Description
  ALL	Log all statement events
  ERRORS	Log only failed statement events
  NONE	Do not log statement events

  Note

  At server startup, any explicit value given for audit_log_statement_policy may be overridden if audit_log_policy is also specified, as described in Section 6.4.5.5, “Configuring Audit Logging Characteristics”.

• audit_log_strategy

  Command-Line Format	--audit-log-strategy=value
  System Variable	audit_log_strategy
  Scope	Global
  Dynamic	No
  Type	Enumeration
  Default Value	ASYNCHRONOUS
  Valid Values	ASYNCHRONOUS PERFORMANCE SEMISYNCHRONOUS SYNCHRONOUS

  The logging method used by the audit log plugin. These strategy values are permitted:

  • ASYNCHRONOUS: Log asynchronously. Wait for space in the output buffer.

  • PERFORMANCE: Log asynchronously. Drop requests for which there is insufficient space in the output buffer.

  • SEMISYNCHRONOUS: Log synchronously. Permit caching by the operating system.

  • SYNCHRONOUS: Log synchronously. Call sync() after each request.

Audit Log Status Variables

If the audit log plugin is enabled, it exposes several status variables that provide operational information. These variables are available for legacy mode audit filtering and JSON mode audit filtering.

• Audit_log_current_size

  The size of the current audit log file. The value increases when an event is written to the log and is reset to 0 when the log is rotated.

• Audit_log_event_max_drop_size

  The size of the largest dropped event in performance logging mode. For a description of logging modes, see Section 6.4.5.5, “Configuring Audit Logging Characteristics”.

• Audit_log_events

  The number of events handled by the audit log plugin, whether or not they were written to the log based on filtering policy (see Section 6.4.5.5, “Configuring Audit Logging Characteristics”).

• Audit_log_events_filtered

  The number of events handled by the audit log plugin that were filtered (not written to the log) based on filtering policy (see Section 6.4.5.5, “Configuring Audit Logging Characteristics”).

• Audit_log_events_lost

  The number of events lost in performance logging mode because an event was larger than the available audit log buffer space. This value may be useful for assessing how to set audit_log_buffer_size to size the buffer for performance mode. For a description of logging modes, see Section 6.4.5.5, “Configuring Audit Logging Characteristics”.

• Audit_log_events_written

  The number of events written to the audit log.

• Audit_log_total_size

  The total size of events written to all audit log files. Unlike Audit_log_current_size, the value of Audit_log_total_size increases even when the log is rotated.

• Audit_log_write_waits

  The number of times an event had to wait for space in the audit log buffer in asynchronous logging mode. For a description of logging modes, see Section 6.4.5.5, “Configuring Audit Logging Characteristics”.