sys.dm_xe_sessions (Transact-SQL)

Applies to: SQL Server Azure SQL Managed Instance

Returns information about server-scoped active extended events sessions. A session is a collection of events, actions, and targets.

Azure SQL Database supports only database-scoped sessions. See sys.dm_xe_database_sessions.

Column name Data type Description
address varbinary(8) The memory address of the session. address is unique across the local system. Is not nullable.
name nvarchar(256) The name of the session. name is unique across the local system. Is not nullable.
pending_buffers int The number of full buffers that are pending processing. Is not nullable.
total_regular_buffers int The total number of regular buffers that are associated with the session. Is not nullable.

Note: Regular buffers are used most of the time. These buffers are of sufficient size to hold many events. Typically, there will be three or more buffers per session. The number of regular buffers is automatically determined by the server, based on the memory partitioning that is set through the MEMORY_PARTITION_MODE option. The size of the regular buffers is equal to the value of the MAX_MEMORY option (default of 4 MB), divided by the number of buffers. For more information about the MEMORY_PARTITION_MODE and the MAX_MEMORY options, see CREATE EVENT SESSION (Transact-SQL).
regular_buffer_size bigint The regular buffer size, in bytes. Is not nullable.
total_large_buffers int The total number of large buffers. Is not nullable.

Note: Large buffers are used when an event is larger than a regular buffer. They are set aside explicitly for this purpose. Large buffers are allocated when the event session starts, and are sized according to the MAX_EVENT_SIZE option. For more information about the MAX_EVENT_SIZE option, see CREATE EVENT SESSION (Transact-SQL).
large_buffer_size bigint The large buffer size, in bytes. Is not nullable.
total_buffer_size bigint The total size of the memory buffer that is used to store events for the session, in bytes. Is not nullable.
buffer_policy_flags int A bitmap that indicates how session event buffers behave when all the buffers are full and a new event is fired. Is not nullable.
buffer_policy_desc nvarchar(256) A description that indicates how session event buffers behave when all the buffers are full and a new event is fired. Is not nullable. buffer_policy_desc can be one of the following values:

Drop event
Do not drop events
Drop full buffer
Allocate new buffer
flags int A bitmap that indicates the flags that have been set on the session. Is not nullable.
flag_desc nvarchar(256) A description of the flags set on the session. Is not nullable. flag_desc can be any combination of the following values:

Flush buffers on close
Dedicated dispatcher
Allow recursive events
dropped_event_count int The number of events that were dropped when the buffers were full. This value is 0 if buffer_policy_desc is "Drop full buffer" or "Do not drop events". Is not nullable.
dropped_buffer_count int The number of buffers that were dropped when the buffers were full. This value is 0 if buffer_policy_desc is set to "Drop event" or "Do not drop events". Is not nullable.
blocked_event_fire_time int The length of time that event firings were blocked when buffers were full. This value is 0 if buffer_policy_desc is "Drop full buffer" or "Drop event". Is not nullable.
create_time datetime The time that the session was created. Is not nullable.
largest_event_dropped_size int The size of the largest event that did not fit into the session buffer. Is not nullable.
session_source nvarchar(256) The scope of the session. Is not nullable. session_source can be one of the following values:

server = session scoped to the server, including user sessions.
internal = certain internal sessions, such as the sp_server_diagnostics session.
buffer_processed_count bigint Applies to: SQL Server 2017 and later. The total number of buffers processed by the session and accumulates from start of session. Is not nullable.
buffer_full_count bigint Applies to: SQL Server 2017 and later. The number of buffers that were full when they were processed and accumulates from start of session. Is not nullable.
total_bytes_generated bigint Applies to: SQL Server 2017 and later. The number of actual bytes that the extended events session has generated. This information is collected when the session is processing buffers and applies to the file target only. No tracking for other targets.
total_target_memory bigint Applies to: SQL Server 2019 and later. The total target memory in bytes for a session storing information in a ring buffer target. Is not nullable.

Permissions

Requires VIEW SERVER STATE permission on the server.

Next steps

Learn more about related concepts in the following articles: