Appendix E: Terminology Mapping

---

This appendix contains the terminology mapping of Oracle to DB2 UDB.

Table 9-14: Oracle Terminology to DB2 UDB mapping

Oracle	DB2 UDB	Comments
Oracle EE	DB2 UDB ESE	Enterprise product
Oracle Parallel	DB2 UDB ESE DPF	Support node partitioning
Oracle Gateway	DB2 Connect	DRDA access to hosts
PL/SQL	SQL Procedural Language	Programming language extension to SQL. DB2 UDB stored procedures can be programmed in SQL Control Statements (subset of PSM standard), Java, C, C++, COBOL, Fortran, OLE, and REXX. DB2 functions can be programmed in Java, C, C++, OLE, or SQL control statements.
SQL*PLUS	DB2 CLP	Command line interface to the server
Instance	Instance	Processes and shared memory. In DB2 it also includes a permanent directory structure: an instance is usually created at install time (or can be later) and must exist before a database can be created. A DB2 instance is also known as the database manager (DBM). A DB2 UDB instance can have multiple databases. But an Oracle instance can only have one database.
Database	Database	Physical structure containing data. In Oracle, multiple instances can use the same database, and an instance can connect to one and only one database. In DB2, multiple databases can be created and used concurrently in the same instance.
Control files and .ora files	DBM and database configuration files, etc.	In Oracle, files that name the locations of files making up the database and provide configuration values. In DB2, each instance (DBM) and database has its own set of configuration parameters stored in a binary file; there are also other internal files and directories: none is manually edited.
Database Link	Federated System	In Oracle, an object that describes a path from one database to another. In DB2 a federated system is used. One database is chosen as the federated database and within it wrappers, servers, nicknames, and other optional objects are created to define how to access the other databases (including Oracle databases) and objects in them. Once an application is connected to the federated database it can access all authorized objects in the federated system.
Table spaces	Table spaces	Contains actual database data
Datafiles	Containers	Entities inside the table spaces
Segments	Objects	Entities inside the containers/data files
Extents	Extents	Entities inside the objects/segments
Data blocks	Pages	Smallest storage entity in the storage model
Clusters	N/A	Data structure that allows related data to be stored together on disk; can be table or hash clusters. The closest facility to this in DB2 is a clustering index, which causes rows inserted into a table to be placed physically close to the rows for which the key values of this index are in the same range.
Data dictionary	System catalog	Metadata of the database
N/A	SMS	System-managed table space
Datafiles	DMS containers	The file and raw devices under Database-managed table space.
Data cache	Buffer pools	Buffers data in the table spaces to reduce disk I/O
Statement cache	Package cache	Caches prepared dynamic SQL statements
Redo logs	Log files	Recovery logs
Rollback segments	N/A	Store the old version of data for a mutating table. In DB2 the old version of an updated row is stored in the log file along with the new version.
SGA	Database manager and database shared memory	Shared memory area(s) for the database server. In Oracle there is one, while in DB2 there is one at the database manager (instance) level any one for each active database.
UGA	Agent / application shared memory	Shared memory area to store user-specific data passed between application process and the database server.
N/A	Package	A precompiled access plan for an embedded static SQL application stored in the server.
Package	N/A	A logical grouping of PL/SQL blocks that can be invoked by other PL/SQL applications.

---