Oracle Database Tips by Donald Burleson

The Concept of Restricted ROWIDs

Oracle used the concept of the restricted rowid in Oracle7 and earlier releases to uniquely identify each row in each table in the database. This was represented as the pseudocolumn rowid in Oracle7 and earlier releases. Hence, unknown to many DBAs and developers, even nonunique identified tables that violated Third Normal Form always had a unique identifier that could be used for removal of duplicates and other unique-identifier-required operations: the rowid column. Of course, views don't have rowids.

Note 

In Oracle8, Oracle8i, and Oracle9i, the concept of rowid is still with us, but the format has been expanded. In Appendix I, on the Wiley Web site, I discuss the DBMS_ROWID set of Oracle-provided packages that provide for rowid manipulation between the old and new formats, and thepiece out as well as the building of rowids.  

But what does a rowid contain? To begin to answer that question, in this chapter we will examine the Oracle7 rowid concepts; in the next chapter, we will cover the expanded rowid (Oracle8, Oracle8i, and Oracle9i types, tables, and such). Though Oracle8i did not add to the concept of rowid, it added some datatypes that deal with rowids; Oracle9i did not add much to the usage of rowids.

Restricted rowid Format

The restricted rowid in Oracle is a VARCHAR2 representation of a binary value shown in hexadecimal format. You should only need to deal with restricted rowids in versions prior to Oracle8 or in systems that were upgraded from Oracle7 to Oracle8, 8i, or 9i. Restricted rowids are displayed as:

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