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sys.dm_xe_sessions (Transact-SQL)

Returns information about an active extended events session. This session is a collection of events, actions, and targets.

Applies to: SQL Server (SQL Server 2008 through current version).

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 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 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. buffer_policy_desc can be one of the following:

  • Drop event

  • Do not drop events

  • Drop full buffer

  • Allocate new buffer

Is not nullable.

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. flag_desc can be any combination of the following:

  • Flush buffers on close

  • Dedicated dispatcher

  • Allow recursive events

Is not nullable.

dropped_event_count

int

The number of events that were dropped when the buffers were full. This value is 0 if the buffer policy 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 the buffer policy 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 the buffer policy 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.

Requires VIEW SERVER STATE permission on the server.

Updated content

Corrected the data type for the name and the blocked_event_fire_time columns.

Removed the buffer_size and total_buffers columns.

Added the total_regular_buffers, regular_buffer_size, total_large_buffers, large_buffer_size and total_buffer_size columns.

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