What Is Object Identity

What is Object Identity?

Is it an internal address? To see if two objects are the same, does one compare each and every value in the object, or check the internal RAM address? An internal RAM address sounds like a form of "record ID" to me. Comparing values seems like nothing more than a long primary key.

The RelationalModel has no concept of "internal RAM address"; that's a low-level implementation detail that is the business of the RDBMS and nobody else.

I meant some kind of unique record/object number. A RAM address is unique (for practical purposes).

A useful source of "identity" might be PrimaryKey (or any CandidateKey) and the containing relation (table)

Object identity in practice is usually just a RAM address. A relational equivalent would probably be something like an auto-generated key. Like an auto-generated key, it is divorced of any domain info to distinqish it from other rows, perhaps risking duplicates. The pro's and con's of such is covered at AutoKeysVersusDomainKeys. --top

Ooops. Move to ObjectIdentity?