In SQL, the MERGE statement is a powerful tool that allows you to perform multiple actions on a single table at once. However, it’s not always the best choice and there are several reasons why you might want to consider using separate INSERT, UPDATE, and DELETE statements instead.
There are a number of issues that can arise when using the MERGE statement, including bugs, performance problems, and concurrency issues. Additionally, many developers prefer the clarity and readability of separate INSERT, UPDATE, and DELETE statements, especially when working with tables that have a large number of columns.
It’s worth noting that while the MERGE statement can be problematic in some cases, it may be necessary to use it in others. For example, in Databricks SQL, the MERGE statement is often the only option. However, in general, it’s best to carefully consider the pros and cons of using the MERGE statement before deciding to implement it in your code.
Here are a few links to better understand why the MERGE statement can be problematic.
Use Caution with SQL Server’s MERGE Statement
Be Careful with the Merge Statement
What To Avoid If You Want To Use MERGE
How MERGE on two different rows can still deadlock you
If you are using indexed views and MERGE, please read this!