What is an indexand why does it need to be rebuilt? An index is what SQL Server uses to retrieve rows from a table. The obvious similarity is to the index of a book; if you need to know about a certain topic, flip to the back and check the index. It tells you right where to find exactly what you’re looking for.
You can have a table without an index defined. In this case, it’s just a heap of data, so it’s termed a heap table. Storing data as a heap isn’t very efficient, as the entire table must be scanned in order to return the data you are requesting in a query. Instead, when you ...
