sys.dm_db_session_space_usage (Transact-SQL)

Applies to: SQL Server Azure SQL Database Azure SQL Managed Instance Azure Synapse Analytics Analytics Platform System (PDW)

Returns the number of pages allocated and deallocated by each session for the database.

Note

This view is applicable only to the tempdb database.

Note

To call this from Azure Synapse Analytics or Analytics Platform System (PDW), use the name sys.dm_pdw_nodes_db_session_space_usage. This syntax is not supported by serverless SQL pool in Azure Synapse Analytics.

Column name	Data type	Description
session_id	smallint	Session ID. session_id maps to session_id in sys.dm_exec_sessions.
database_id	smallint	Database ID. In Azure SQL Database, the values are unique within a single database or an elastic pool, but not within a logical server.
user_objects_alloc_page_count	bigint	Number of pages reserved or allocated for user objects by this session.
user_objects_dealloc_page_count	bigint	Number of pages deallocated and no longer reserved for user objects by this session.
internal_objects_alloc_page_count	bigint	Number of pages reserved or allocated for internal objects by this session.
internal_objects_dealloc_page_count	bigint	Number of pages deallocated and no longer reserved for internal objects by this session.
user_objects_deferred_dealloc_page_count	bigint	Number of pages which have been marked for deferred deallocation. Note: Introduced in service packs for SQL Server 2012 (11.x) and SQL Server 2014 (12.x).
pdw_node_id	int	Applies to: Azure Synapse Analytics, Analytics Platform System (PDW) The identifier for the node that this distribution is on.

Permissions

On SQL Server and SQL Managed Instance, requires VIEW SERVER STATE permission.

On SQL Database Basic, S0, and S1 service objectives, and for databases in elastic pools, the server admin account, the Microsoft Entra admin account, or membership in the ##MS_ServerStateReader## server role is required. On all other SQL Database service objectives, either the VIEW DATABASE STATE permission on the database, or membership in the ##MS_ServerStateReader## server role is required.

Permissions for SQL Server 2022 and later

Requires VIEW SERVER PERFORMANCE STATE permission on the server.

Remarks

IAM pages are not included in any of the allocation or deallocation counts reported by this view.

Page counters are initialized to zero (0) at the start of a session. The counters track the total number of pages that have been allocated or deallocated for tasks that are already completed in the session. The counters are updated only when a task ends; they do not reflect running tasks.

A session can have multiple requests active at the same time. A request can start multiple threads, tasks, if it is a parallel query.

For more information about the sessions, requests, and tasks, see sys.dm_exec_sessions (Transact-SQL), sys.dm_exec_requests (Transact-SQL), and sys.dm_os_tasks (Transact-SQL).

User objects

The following objects are included in the user object page counters:

• User-defined tables and indexes

• System tables and indexes

• Global temporary tables and indexes

• Local temporary tables and indexes

• Table variables

• Tables returned in the table-valued functions

Internal objects

Internal objects are only in tempdb. The following objects are included in the internal object page counters:

• Work tables for cursor or spool operations and temporary large object (LOB) storage

• Work files for operations such as a hash join

• Sort runs

Physical joins

Relationship cardinalities

From	To	Relationship
dm_db_session_space_usage.session_id	dm_exec_sessions.session_id	One-to-one

Next steps

Dynamic Management Views and Functions (Transact-SQL)
Database Related Dynamic Management Views (Transact-SQL)
sys.dm_exec_sessions (Transact-SQL)
sys.dm_exec_requests (Transact-SQL)
sys.dm_os_tasks (Transact-SQL)
sys.dm_db_task_space_usage (Transact-SQL)
sys.dm_db_file_space_usage (Transact-SQL)