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Oracle ROWID and its Uniqueness

ROWID Data Type

Oracle Database uses a ROWID datatype to store the address (rowid) of every row in the database.

Physical rowids store the addresses of rows in ordinary tables (excluding index-organized tables), clustered tables, table partitions and subpartitions, indexes, and index partitions and subpartitions.
Logical rowids store the addresses of rows in index-organized tables.

A single datatype called the universal rowid, or UROWID, supports both logical and physical rowids, as well as rowids of foreign tables such as non-Oracle tables accessed through a gateway.

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