sys-dm-tran-top-version-generators-transact-sql.md

title	description	author	ms.author	ms.date	ms.service	ms.subservice	ms.topic	f1_keywords	helpviewer_keywords	dev_langs	monikerRange
sys.dm_tran_top_version_generators (Transact-SQL)	sys.dm_tran_top_version_generators (Transact-SQL)	rwestMSFT	randolphwest	06/19/2023	sql	system-objects	reference	dm_tran_top_version_generators sys.dm_tran_top_version_generators dm_tran_top_version_generators_TSQL sys.dm_tran_top_version_generators_TSQL	sys.dm_tran_top_version_generators dynamic management view	TSQL	>=aps-pdw-2016||=azuresqldb-current||=azure-sqldw-latest||>=sql-server-2016||>=sql-server-linux-2017||=azuresqldb-mi-current

sys.dm_tran_top_version_generators (Transact-SQL)

[!INCLUDE sql-asdb-asdbmi-asa-pdw]

Returns a virtual table for the objects that are producing the most versions in the version store. sys.dm_tran_top_version_generators returns the top 256 aggregated record lengths that are grouped by the database_id and rowset_id. sys.dm_tran_top_version_generators retrieves data by querying the dm_tran_version_store virtual table. sys.dm_tran_top_version_generators is an inefficient view to run because this view queries the version store, and the version store can be very large. We recommend that you use this function to find the largest consumers of the version store.

Note

To call this from [!INCLUDEssazuresynapse-md] or [!INCLUDEssPDW], use the name sys.dm_pdw_nodes_tran_top_version_generators. [!INCLUDEsynapse-analytics-od-unsupported-syntax]

Syntax

  
sys.dm_tran_top_version_generators  

Table Returned

Column name	Data type	Description
database_id	int	Database ID. In [!INCLUDE ssazure-sqldb], the values are unique within a single database or an elastic pool, but not within a logical server.
rowset_id	bigint	Rowset ID.
aggregated_record_length_in_bytes	int	Sum of the record lengths for each database_id and rowset_id pair in the version store.
pdw_node_id	int	Applies to: [!INCLUDEssazuresynapse-md], [!INCLUDEssPDW] The identifier for the node that this distribution is on.

Permissions

On [!INCLUDEssNoVersion_md] 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

Because sys.dm_tran_top_version_generators might have to read many pages as it scans the entire version store, running sys.dm_tran_top_version_generators can interfere with system performance.

Examples

The following example uses a test scenario in which four concurrent transactions, each identified by a transaction sequence number (XSN), are running in a database that has the ALLOW_SNAPSHOT_ISOLATION and READ_COMMITTED_SNAPSHOT options set to ON. The following transactions are running:

• XSN-57 is an update operation under serializable isolation.

• XSN-58 is the same as XSN-57.

• XSN-59 is a select operation under snapshot isolation.

• XSN-60 is the same as XSN-59.

The following query is executed.

SELECT  
    database_id,  
    rowset_id,  
    aggregated_record_length_in_bytes  
  FROM sys.dm_tran_top_version_generators;  

[!INCLUDEssResult]

database_id rowset_id            aggregated_record_length_in_bytes  
----------- -------------------- ---------------------------------  
9           72057594038321152    87  
9           72057594038386688    33  

The output shows that all versions are created by database_id``9 and that the versions generate from two tables.

See also

Dynamic Management Views and Functions (Transact-SQL)
Transaction Related Dynamic Management Views and Functions (Transact-SQL)