The hash function used everywhere in Oracle

 Hi All, I am sorry the subject is a little confusing. what I exactly mean here is that Oracle itself uses hash algorithm a lot. But duplication is the problem which can't be resolved by hash algorithm in nature. So I guess full text matching is required for almost all the cases.

 And I will give some examples to make myself clearer.

1. Logon. As all of us know, the passwords are stored in a hashed format. There is likelihood (no matter how low) that  two differenct     passwords will be hashed to the same one.

2. Hash join. In this case, two tables are hased to match. Since it is not uncommont that both of two tables has billions of rows, the likelihood to generate duplication is higher than item 1.