Multithreaded database access

Question

On my c# project, i have an SQL connection in MARS mode that is being used by multiple threads to perform CRUD operations. Some of these operations are required to be performed as a transaction. After i completed the data access module, i started testing and got an InvalidOperationException from one of the selects, stating that since the connection had an active transaction, the select itself needed to be in a transaction. Snooping around MSDN i found the following remark:

Caution: When your query returns a large amount of data and calls BeginTransaction, a SqlException is thrown because SQL Server does not allow parallel transactions when using MARS. To avoid this problem, always associate a transaction with the command, the connection, or both before any readers are open.

I could easily create a method that would aggregate commands into a transaction, this would even allow me to have a timer thread committing transactions on a regular interval, but is this the right way? Should i instead halt commands that don't need a transaction until an active transaction is committed?

Answer 1

I would stay away from MARS.

See:

used by multiple threads to perform CRUD operations

That screams "every thread one connection, and it's own transaction" unless you have a very rare case here. This absolutely does not sound like a valid use case for MARS.