sys.fn_get_audit_file_v2 (Transact-SQL)

  • Article

Applies to: Azure SQL Database

The sys.fn_get_audit_file_v2 system function in Azure SQL Database is designed to retrieve audit log data with enhanced efficiency compared to its predecessor, sys.fn_get_audit_file. The function introduces time-based filtering at both the file and record levels, providing significant performance improvements, particularly for queries targeting specific time ranges.

Important

sys.fn_get_audit_file_v2 is currently supported on Azure SQL Database only.

Returns information from an audit file created by a server audit in Azure SQL Database. For more information, see SQL Server Audit (Database Engine).

Transact-SQL syntax conventions

Syntax

fn_get_audit_file_v2 ( file_pattern
    , { default | initial_file_name | NULL }
    , { default | audit_record_offset | NULL }
    , { default | start time | NULL }
    , { default | end time | NULL } )

Arguments

file_pattern

Specifies the directory or path and file name for the audit file set to be read. file_pattern is nvarchar(260).

Passing a path without a file name pattern generates an error.

This argument is used to specify a blob URL (including the storage endpoint and container). While it doesn't support an asterisk wildcard, you can use a partial file (blob) name prefix (instead of the full blob name) to collect multiple files (blobs) that begin with this prefix. For example:

  • <Storage_endpoint>/<Container>/<ServerName>/<DatabaseName>/ - collects all audit files (blobs) for the specific database.

  • <Storage_endpoint>/<Container>/<ServerName>/<DatabaseName>/<AuditName>/<CreationDate>/<FileName>.xel - collects a specific audit file (blob).

initial_file_name

Specifies the path and name of a specific file in the audit file set to start reading audit records from. initial_file_name is nvarchar(260).

The initial_file_name argument must contain valid entries or must contain either the default or NULL value.

audit_record_offset

Specifies a known location with the file specified for the initial_file_name. When this argument is used, the function starts reading at the first record of the buffer immediately following the specified offset.

The audit_record_offset argument must contain valid entries or must contain either the default or NULL value. audit_record_offset is bigint.

start_time

The start time for filtering the logs. Records before this time are excluded.

end_time

The end time for filtering the logs. Records after this time are excluded.

Table returned

The following table describes the audit file content returned by this function.

Column name Type Description
event_time datetime2 Date and time when the auditable action is fired. Not nullable.
sequence_number int Tracks the sequence of records within a single audit record that was too large to fit in the write buffer for audits. Not nullable.
action_id varchar(4) ID of the action. Not nullable.
succeeded bit Indicates whether the action that triggered the event succeeded. Not nullable. For all events other than login events, this only reports whether the permission check succeeded or failed, not the operation.

1 = success
0 = fail
permission_bitmask varbinary(16) In some actions, this bitmask is the permissions that were grant, denied, or revoked.
is_column_permission bit Flag indicating if this is a column level permission. Not nullable. Returns 0 when the permission_bitmask = 0.

1 = true
0 = false
session_id smallint ID of the session on which the event occurred. Not nullable.
server_principal_id int ID of the login context that the action is performed in. Not nullable.
database_principal_id int ID of the database user context that the action is performed in. Not nullable. Returns 0 if this doesn't apply. For example, a server operation.
target_server_principal_id int Server principal that the GRANT/DENY/REVOKE operation is performed on. Not nullable. Returns 0 if not applicable.
target_database_principal_id int The database principal the GRANT/DENY/REVOKE operation is performed on. Not nullable. Returns 0 if not applicable.
object_id int The ID of the entity on which the audit occurred, which includes the following objects:

- Server objects
- Databases
- Database objects
- Schema objects

Not nullable. Returns 0 if the entity is the Server itself or if the audit isn't performed at an object level. For example, Authentication.
class_type varchar(2) The type of auditable entity that the audit occurs on. Not nullable.
session_server_principal_name sysname Server principal for session. Nullable. Returns the identity of the original login that was connected to the instance of the Database Engine in case there were explicit or implicit context switches.
server_principal_name sysname Current login. Nullable.
server_principal_sid varbinary Current login SID. Nullable.
database_principal_name sysname Current user. Nullable. Returns NULL if not available.
target_server_principal_name sysname Target login of action. Nullable. Returns NULL if not applicable.
target_server_principal_sid varbinary SID of target login. Nullable. Returns NULL if not applicable.
target_database_principal_name sysname Target user of action. Nullable. Returns NULL if not applicable.
server_instance_name sysname Name of the server instance where the audit occurred. The standard server\instance format is used.
database_name sysname The database context in which the action occurred. Nullable. Returns NULL for audits occurring at the server level.
schema_name sysname The schema context in which the action occurred. Nullable. Returns NULL for audits occurring outside a schema.
object_name sysname The name of the entity on which the audit occurred, which includes the following objects:

- Server objects
- Databases
- Database objects
- Schema objects

Nullable. Returns NULL if the entity is the Server itself or if the audit isn't performed at an object level. For example, Authentication.
statement nvarchar(4000) Transact-SQL statement if it exists. Nullable. Returns NULL if not applicable.
additional_information nvarchar(4000) Unique information that only applies to a single event is returned as XML. A few auditable actions contain this kind of information.

One level of T-SQL stack is displayed in XML format for actions that have T-SQL stack associated with them. The XML format is: <tsql_stack><frame nest_level = '%u' database_name = '%.*s' schema_name = '%.*s' object_name = '%.*s' /></tsql_stack>

frame nest_level indicates the current nesting level of the frame. The module name is represented in three part format (database_name, schema_name, and object_name). The module name is parsed to escape invalid XML characters like <, >, /, _x. They're escaped as _xHHHH_. The HHHH stands for the four-digit hexadecimal UCS-2 code for the character. Nullable. Returns NULL when there's no additional information reported by the event.
file_name varchar(260) The path and name of the audit log file that the record came from. Not nullable.
audit_file_offset bigint The buffer offset in the file that contains the audit record. Not nullable.

Applies to: SQL Server only
user_defined_event_id smallint User defined event ID passed as an argument to sp_audit_write. NULL for system events (default) and non-zero for user-defined event. For more information, see sp_audit_write (Transact-SQL).

Applies to: SQL Server 2012 (11.x) and later, Azure SQL Database, and SQL Managed Instance
user_defined_information nvarchar(4000) Used to record any extra information the user wants to record in audit log by using the sp_audit_write stored procedure.

Applies to: SQL Server 2012 (11.x) and later versions, Azure SQL Database, and SQL Managed Instance
audit_schema_version int Always 1.
sequence_group_id varbinary Unique identifier.

Applies to: SQL Server 2016 (13.x) and later versions
transaction_id bigint Unique identifier to identify multiple audit events in one transaction.

Applies to: SQL Server 2016 (13.x) and later versions
client_ip nvarchar(128) Source IP of the client application.

Applies to: SQL Server 2017 (14.x) and later versions, and Azure SQL Database
application_name nvarchar(128) Name of client application that executed the statement that caused the audit event.

Applies to: SQL Server 2017 (14.x) and later versions, and Azure SQL Database
duration_milliseconds bigint Query execution duration in milliseconds.

Applies to: Azure SQL Database and SQL Managed Instance
response_rows bigint Number of rows returned in the result set.

Applies to: Azure SQL Database and SQL Managed Instance
affected_rows bigint Number of rows affected by the executed statement.

Applies to: Azure SQL Database only
connection_id uniqueidentifier ID of the connection in the server.

Applies to: Azure SQL Database and SQL Managed Instance
data_sensitivity_information nvarchar(4000) Information types and sensitivity labels returned by the audited query, based on the classified columns in the database. Learn more about Azure SQL Database data discover and classification.

Applies to: Azure SQL Database only
host_name nvarchar(128) Host Name of the client machine.
session_context nvarchar(4000) The key-value pairs that are a part of the current session context.
client_tls_version bigint Minimum TLS version supported by the client.
client_tls_version_name nvarchar(128) Minimum TLS version supported by the client.
database_transaction_id bigint Transaction ID of the current transaction in the current session.
ledger_start_sequence_number bigint The sequence number of an operation within a transaction that created a row version.

Applies to: Azure SQL Database only
external_policy_permissions_checked nvarchar(4000) Information related to the external authorization permission check, when an audit event is generated, and Purview external authorization policies are evaluated.

Applies to: Azure SQL Database only
obo_middle_tier_app_id varchar(120) The application ID of the middle tier application that connects to Azure SQL Database using on-behalf-of (OBO) access. Nullable. Returns NULL if the request isn't made using OBO access.

Applies to: Azure SQL Database only
is_local_secondary_replica bit True if the audit record originates from a read-only local secondary replica, False otherwise.

Applies to: Azure SQL Database only

Improvements over sys.fn_get_audit_file

The sys.fn_get_audit_file_v2 function offers a substantial improvement over the older sys.fn_get_audit_file by introducing efficient time-based filtering at both the file and record levels. This optimization is particularly beneficial for queries targeting smaller time ranges and can help maintain performance in multi-database environments.

Dual-level filtering

File-level filtering: The function first filters the files based on the specified time range, reducing the number of files that need to be scanned.

Record-level filtering: It then applies filtering within the selected files to extract only the relevant records.

Performance enhancements

The performance improvements are primarily dependent on the rollover time of the blob files and the queried time range. Assuming a uniform distribution of audit records:

  • Reduced load: By minimizing the number of files and records to scan, it reduces the load on the system and improves query response times.

  • Scalability: Helps maintain performance even as the number of databases increases, though the net improvement might be less pronounced in environments with a high number of databases.

For information on setting up Azure SQL Database auditing, see Get Started with SQL Database auditing.

Remarks

  • If the file_pattern argument passed to fn_get_audit_file_v2 references a path or file that doesn't exist, or if the file isn't an audit file, the MSG_INVALID_AUDIT_FILE error message is returned.

  • fn_get_audit_file_v2 can't be used when the audit is created with the APPLICATION_LOG, SECURITY_LOG, or EXTERNAL_MONITOR options.

Permissions

Requires the CONTROL DATABASE permission.

  • Server admins can access audit logs of all databases on the server.

  • Non server admins can only access audit logs from the current database.

  • Blobs that don't meet the above criteria are skipped (a list of skipped blobs is displayed in the query output message). The function returns logs only from blobs for which access is allowed.

Examples

This example retrieves audit logs from a specific Azure Blob Storage location, filtering records between 2023-11-17T08:40:40Z and 2023-11-17T09:10:40Z.

SELECT *
FROM sys. fn_get_audit_file_v2(
    'https://yourstorageaccount.blob.core.windows.net/sqldbauditlogs/server_name/database_name/SqlDbAuditing_ServerAudit/',
    DEFAULT,
    DEFAULT,
    '2023-11-17T08:40:40Z',
    '2023-11-17T09:10:40Z')

More information

System catalog views:

Transact-SQL:

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