Press "Enter" to skip to content

Halloween Protection and Non-Clustered Indexes

Jared Poche digs further into Halloween protection:

I find myself talking about the Halloween Problem a lot and wanted to fill in some more details on the subject. In short, the Halloween Problem is a case where an INSERT\UPDATE\DELETE\MERGE operates on a row more than once, or tries to and fails. In the first recorded case, an UPDATE changed multiple rows in the table more than once.

So let’s take a look at an example using a publicly available database, WideWorldImporters.

Read on for a case of Jared starting from the known and moving into the unknown.