While working with SQL Server, you may come across situations where you need to optimize the performance of your queries. One way to achieve this is by using query optimizer hints. In this article, we will explore the concept of query optimizer hints and specifically focus on the “ROBUST PLAN” hint.

What are Query Optimizer Hints?

Query optimizer hints are T-SQL clauses that provide instructions to the SQL Server query optimizer on how to execute a query. These hints can suggest the use of specific indexes, joins, or other logical operations to improve query performance. By default, SQL Server’s query optimizer selects the best execution plan for a query. However, in certain scenarios, using query optimizer hints can help achieve better performance.

The “ROBUST PLAN” Hint

The “ROBUST PLAN” hint is a unique query optimizer hint that addresses a specific issue related to oversized rows. In some cases, a table may contain a row that is too large for certain operations, causing the query to crash. The “ROBUST PLAN” hint allows the query optimizer to ignore these oversized rows and prevent the query from failing.

It’s important to note that this issue is not related to the maximum row size limit of 2 GB in SQL Server 2005. Instead, it pertains to operations that consider a given row to be too large, even if it is within the size limit.

Practical Example

While researching this topic, I was unable to find a specific example where the “ROBUST PLAN” hint was necessary. However, I believe this hint can be useful in scenarios where a query fails to produce any result and generates an error. By using the “ROBUST PLAN” hint, you can at least expect to obtain some answer, albeit with reduced performance in certain cases.

If you have encountered a situation where the “ROBUST PLAN” hint was required, I invite you to share your experience. Please provide a query that runs successfully with the “ROBUST PLAN” hint, but fails without it. I will include your example in this article with proper credit.

Query optimizer hints, including the “ROBUST PLAN” hint, can be a powerful tool in optimizing query performance. However, it is important to use them judiciously and only when necessary. The SQL Server query optimizer is designed to handle most optimization tasks automatically, so it is generally recommended to rely on its default behavior.

Thank you for reading this article. I hope you found it informative and gained a better understanding of query optimizer hints in SQL Server.