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)