Clustered Index Uniquifier Existence and Size

In SQL Server, Clustered Indexes created without the UNIQUE keyword must guarantee unique key values by adding a hidden "uniquifier". But how big is this field, and is it always there?

Impact on Indexes When Mixing VARCHAR and NVARCHAR Types

You may have heard, or read, that you should not mix VARCHAR and NVARCHAR datatypes, especially when one of them is a JOIN or WHERE predicate / condition, as doing so will invalidate indexes. While it is always best to have all datatypes be the same for a particular operation (comparison, concatenation, etc), the actual… Continue reading Impact on Indexes When Mixing VARCHAR and NVARCHAR Types