Is it faster to search for a large string in a DB by its hashcode?

Question

If I need to retrieve a large string from a DB, Is it faster to search for it using the string itself or would I gain by hashing the string and storing the hash in the DB as

Answer 1

I am confused and am probably misunderstanding your question.

If you already have the string (thus you can compute the hash), why do you need to retrieve it?

Do you use a large string as the key for something perhaps?