How to Review transaction order and lock acquisition in SQL Server

In SQL Server, you can review the transaction order and lock acquisition by analysing the queries and transactions that are being executed against the database. Here are some approaches to review transaction order and lock acquisition:

1. Transaction isolation levels:

   • Review the transaction isolation levels used in your database transactions. Isolation levels such as Read Uncommitted, Read Committed, Repeatable Read, and Serializable can impact the order of lock acquisition and the behaviour of concurrent transactions.

2. Query execution plans:

   • Use SQL Server Management Studio (SSMS) or other database management tools to analyse the query execution plans for your transactions.
   • The execution plans can provide insights into the order in which data is accessed and the types of locks acquired during query execution.

3. Locking and blocking:

   • Monitor and analyse the locking and blocking behaviour of concurrent transactions using tools like SQL Server Profiler, Extended Events, or dynamic management views (DMVs) such as sys.dm_tran_locks and sys.dm_os_waiting_tasks.
   • Identify instances of blocking and analyse the lock types and resources involved to understand the order of lock acquisition.

4. Transaction log and history:

   • Review the transaction log and history to understand the sequence of transactions and their impact on lock acquisition.
   • SQL Server's transaction log and history can provide valuable information about the order in which transactions are executed and their associated locks.

By using these approaches, you can gain insights into the transaction order and lock acquisition behaviour in SQL Server, which can help in identifying potential issues related to deadlocks, blocking, and overall transaction concurrency.