Can SQL Server EXEC Statements Run in Parallel?

Asynchronous Procedure Execution in SQL Server

In the context of SQL Server 2008 R2, a common query involves executing two statements sequentially:

EXECUTE sp_executesql N'PRINT ''1st '' + convert(varchar, getdate(), 126) WAITFOR DELAY ''000:00:10'''
EXECUTE sp_executesql N'PRINT ''2nd '' + convert(varchar, getdate(), 126)'

However, the second statement remains unexecuted until the first one completes. This sequential execution can be problematic, especially when the first statement has a significant delay.

Can EXEC Statements Be Executed in Parallel?

The question arises: is it possible to execute these statements in parallel to optimize performance? While SQL Server allows for asynchronous procedure execution, this approach may not be the most appropriate solution in this case.

Asynchronous Procedure Execution

Asynchronous procedure execution enables stored procedures to be executed in a separate SQL Server session. This separation allows the first statement to continue its execution without blocking the second statement. However, asynchronous procedure execution is primarily designed for requests that are independent and do not have dependencies on each other.

Data Access and Parallelism

It is important to recognize that T-SQL operates primarily as a data access language. When dealing with transactions, locking, and commit/rollback operations, achieving true parallelism is challenging. Parallel T-SQL is typically employed in scenarios involving request queues, where each request is independent and lacks inter-job correlation.

Alternative Approaches

In the context of the example provided, where the objective is to obtain a record, lock it, and subsequently execute other statements while it is locked, parallelization may not be the optimal solution. Instead, consider using table lock mechanisms and thread management techniques to manage concurrent access and data manipulation.

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