Why not use varchar(max)?

Question

I\'m a bit old school when it comes to database design, so I\'m totally for using the correct data sizes in columns. However, when reviewing a database for a friend, I notic

Answer 1

They should NOT be used unless you expect large amounts of data and here is the reason why (directly from Books Online):

Columns that are of the large object (LOB) data types ntext, text, varchar(max), nvarchar(max), varbinary(max), xml, or image cannot be specified as key columns for an index.

If you want to cripple performance, use nvarchar for everything.