Michael Valentine Jones (2/26/2015)
I have done this in order to avoid having to create an index on the string column.Since this column is a unique identifier, you would probably still need a unique index or or unique constraint, so I doubt you would see much benefit.
This is what I have done so far. Checksum doesn't guarantee uniqueness, but is quite fast. I added an index on the computed checksum column (thus the need for a persistent computed column). Depending on the scenario, I would add the string itself in the "include" portion of the index.