|Oracle 8i Data Cartridge Developer's Guide
Release 2 (8.1.6)
Part Number A76937-01
Defining Object Types , 3 of 5
TYPE statement has an optional keyword
OID, which associates a user-specified object identifier (
OID) with the type definition. This feature was available effective with release 8.0.3; however, it was not documented because it is intended for use primarily by Oracle product developers and by developers of data cartridges. However, it should be used by anyone who creates an object type that will be used in more than one database.
Each type has an
OID. If you create an object type and do not specify an
OID, Oracle generates an
OID and assigns it to the type. Oracle8i uses the
OID internally for operations pertaining to that type. Using the same
OID for a type is important if you plan to share instances of the type across databases for such operations as export/import and distributed queries.
For example, assume that you want to create a type named SpecialPerson and then instantiate that type in two different databases with tables named SpecialPersonTable1 and SpecialPersonTable2. The RDBMS needs to know that the SpecialPerson type is the same type in both instances, and therefore the type must be defined using the same
OID in both databases. If you do not specify an
TYPE, a unique identifier is created automatically by the RDBMS.
The syntax for specifying an
OID for an object type is as follows:
In the following example, the
SELECT statement generates an
OID, and the
TYPE statement uses the
OID in creating an object type named mytype. Be sure to use the
SELECT statement to generate a different
OID for each object type to be created, because this is the only way to guarantee that each
OID is valid and globally unique.