Optimized Locking - Transaction ID (TID) Locking internals sample

[segovoni]

This PR introduces documentation and setup scripts for understanding Transaction ID (TID) locking internals in SQL Server 2025's Optimized Locking feature.

[uc-msft]

Can you modify the script as commented & remove use of DBCC commands?

[uc-msft]

You don't need to use DBCC commands to get the TID information when there is a transaction lock. DBCC commands are not supported in Azure SQL Database also. It is desirable for samples to work on all platforms.

The sys.dm_tran_locks DMV exposes the TID locks as a new resource type = XACT. See the DMV documentation for more details on the exact scenarios.

You can instead do:

BEGIN TRANSACTION
INSERT INTO dbo.TelemetryPacket DEFAULT VALUES;
INSERT INTO dbo.TelemetryPacket DEFAULT VALUES;
INSERT INTO dbo.TelemetryPacket DEFAULT VALUES;

select l.resource_description, l.resource_associated_entity_id, l.resource_lock_partition, l.request_mode, l.request_type, l.request_status, l.request_owner_type
  from sys.dm_tran_locks as l
 where l.request_session_id = @@SPID
   and l.resource_type = 'XACT';
ROLLBACK;

[segovoni]

HI @uc-msft,

thanks for your review. As requested I removed DBCC commands not supported in Azure SQL Database and added the query on the sys.dm_tran_locks DMV to inspect TID value during the transaction.