Merge pull request #22285 from MicrosoftDocs/MikeRayMSFT-patch-2

Update ADR

Author: PRMerger14

docs/relational-databases/accelerated-database-recovery-concepts.md

@@ -156,7 +156,24 @@ There are several improvements to address persistent version store (PVS) storage
 
 - **Multi-threaded version cleanup**  
 
-  In [!INCLUDE[sssql19-md](../includes/sssql19-md.md)], the cleanup process is single threaded within a SQL Server instance. In [!INCLUDE[sssql22-md](../includes/sssql22-md.md)], the clean up process will have multiple threads, with one thread per SQL Server database.
+  In [!INCLUDE[sssql19-md](../includes/sssql19-md.md)], the cleanup process is single threaded within a SQL Server instance. In SQL Server 2022 (16.x) Preview, the cleanup process has multiple threads, with one thread per SQL Server database. 
+  
+  In [!INCLUDE[sssql22-md](../includes/sssql22-md.md)], CTP 2.0, you can also enable multi-threaded version cleanup at the database level with trace flag 3515. This allows multiple threads for cleanup per database. This improvement is valuable when you have a fewer number of large databases.
+To enable trace flag 3515 for the instance, run the following command:
+
+   ```sql
+   DBCC TRACEON(3515, -1)
+   GO 
+   ```
+
+  To adjust the number of threads for version cleanup scalability, set `ADR Cleaner Thread Count` with `sp_configure`.   
+
+  The example below changes the thread count to 4: 
+
+  ```sql
+  EXEC sp_configure 'ADR Cleaner Thread Count', '4'
+  RECONFIGURE WITH OVERRIDE; 
+  ```
 
 ## Best practices and guidance
 

docs/sql-server/what-s-new-in-sql-server-2022.md

@@ -105,7 +105,7 @@ The following sections provide an overview of these features.
 |:---|:---|
 | Setup attached to Azure | Install Azure Arc agent via SQL Server at setup. For more information, see [Install SQL Server from the Command Prompt](../database-engine/install-windows/install-sql-server-from-the-command-prompt.md#install-sql-server-from-the-command-prompt).|
 | Max server memory calculations | During setup, the installation will configure max server memory to align with recommendations. See [Server memory configuration options](../database-engine/configure-windows/server-memory-server-configuration-options.md). |
-| Accelerated Database Recovery (ADR) improvements | There are several improvements to address persistent version store (PVS) storage and improve overall scalability. SQL Server 2022 implements a persistent version store cleaner thread per database instead of per instance and the memory footprint for PVS page tracker has been improved. There are also a number of ADR efficiency improvements, such as concurrency improvements that help the cleanup process to work more efficiently. ADR cleans pages that couldn't previously be cleaned due to locking.<br/><br/>See [Restore and Recovery Overview (SQL Server)](../relational-databases/backup-restore/restore-and-recovery-overview-sql-server.md#adr).|
+| Accelerated Database Recovery (ADR) improvements | There are several improvements to address persistent version store (PVS) storage and improve overall scalability. SQL Server 2022 implements a persistent version store cleaner thread per database instead of per instance and the memory footprint for PVS page tracker has been improved. There are also a number of ADR efficiency improvements, such as concurrency improvements that help the cleanup process to work more efficiently. ADR cleans pages that couldn't previously be cleaned due to locking.<br/><br/>See [ADR improvements in SQL Server 2022 (16.x) Preview](../relational-databases/accelerated-database-recovery-concepts.md#adr-improvements-in-).|
 | Improved snapshot backup support |  Adds Transact-SQL support for freezing and thawing I/O without requiring a VDI client. [Create a Transact-SQL snapshot backup](../relational-databases/backup-restore/create-a-transact-sql-snapshot-backup.md).|
 | Shrink database wait with low priority | In previous releases, shrinking databases and database files to reclaim space often leads to concurrency issues. In SQL Server 2022 an additional option for DBCC SHRINKDATABASE and DBCC SHRINKFILE 'WAIT_AT_LOW_PRIORITY' changes the default behavior. When specifying WAIT_AT_LOW_PRIORITY behavior, new queries requiring Sch-S locks aren't blocked by the waiting shrink operation, until the shrink operation stops waiting and begins executing. See [WAIT_AT_LOW_PRIORITY](../relational-databases/databases/shrink-a-database.md#remarks).|
 | Asynchronous auto update statistics concurrency|Avoid potential concurrency issues using asynchronous statistics update if you enable the ASYNC_STATS_UPDATE_WAIT_AT_LOW_PRIORITY [database-scoped configuration](../t-sql/statements/alter-database-scoped-configuration-transact-sql.md).|