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'd be surprised if this offered huge improvement and I would recommend not using your own performance optimisations for a DB search.

If you use a database index there is scope for performance to be tuned by a DBA using tried and trusted methods. Hard coding your own index optimisation will prevent this and may stop you gaining for any performance improvements in indexing in future versions of the DB.