When working with transactional publications in SQL Server, we often think of articles as tables. However, it’s important to note that articles can actually be other objects, including stored procedures. In this article, we will explore the concept of replicating stored procedures in SQL Server and discuss the benefits and considerations associated with this approach.
To get started, let’s assume we have a database with a single table called Employees and two stored procedures: one to add an employee and another to increase the pay of all employees. We can configure our publication to include these stored procedures as articles. By doing so, any changes made to these stored procedures on the publisher will be automatically propagated to the subscriber.
There are three options for replicating stored procedures: ‘Stored Procedure Definition Only’, ‘Stored Procedure Execution’, and ‘Execution in a serialized transaction of the SP’.
The ‘Stored Procedure Definition Only’ option replicates only the definition of the stored procedure. This is useful if you plan to use the subscriber as a standby server or if you’ve configured replication for updating subscribers. The stored procedure will not be called as part of standard replication.
The ‘Stored Procedure Execution’ option replicates the execution of the stored procedure. This can be a huge performance advantage, especially when updating or deleting large numbers of rows. Instead of transmitting a replication procedure call for each row changed, the same stored procedure is executed on the subscriber(s). This reduces the amount of work and network traffic required.
The last option, ‘Execution in a serialized transaction of the SP’, replicates the stored procedure execution within a serialized transaction with the isolation level set to SERIALIZABLE. This ensures absolute perfection and eliminates the chance of the stored procedure affecting a different number of rows due to concurrent transactions. However, this option may have a negative impact on concurrency and should be used judiciously.
When deciding which option to choose, it’s important to consider factors such as data access patterns, tolerance for slightly different data, and network performance. If you have a slow network connection or frequently update or delete large numbers of rows, replicating stored procedure execution can significantly reduce latency and improve performance. However, if data accuracy is critical and you require absolute perfection, the serialized transaction option may be the way to go.
It’s worth noting that you can selectively choose which stored procedures to replicate and whether they should be serialized or not. For example, you can create a dedicated stored procedure for administrative tasks and replicate its execution. This allows you to modify the stored procedure as needed and run it on the publisher during off-peak hours, ensuring that the right definition is available on each subscriber at the right time.
In conclusion, replicating stored procedures in SQL Server can provide significant performance benefits and reduce network traffic. By carefully considering your specific requirements and data access patterns, you can choose the appropriate replication option and optimize the replication process for your environment.