DB2 Version 9.7 for Linux, UNIX, and Windows
DB2 Version 9.7 for Linux, UNIX, and Windows
Because Oracle applications can be enabled to work with DB2® data servers when the DB2 environment is set up appropriately, it is important to understand how certain Oracle concepts map to DB2 concepts.
Table 1 provides a concise summary of commonly used Oracle terms and their DB2 equivalents.
| Oracle concept | DB2 concept | Notes |
|---|---|---|
| active log | active log | This is the same concept. |
| actual parameter | argument | This is the same concept. |
| alert log | db2diag log files and administration notification log | The db2diag log files are primarily intended for use by IBM Software Support for troubleshooting purposes. The administration notification log is primarily intended for troubleshooting use by database and system administrators. Administration notification log messages are also logged to the db2diag log files using a standardized message format. |
| archive log | offline-archive log | This is the same concept. |
| archive log mode | log archiving | This is the same concept. |
| background_dump_dest | diagpath | This is the same concept. |
| created global temporary table | created global temporary table | This is the same concept. |
| cursor sharing | statement concentrator | This is the same concept. |
| data block | data page | This is the same concept. |
| data buffer cache | buffer pool | This is the same concept. However, in DB2 you can have as many buffer pools of any page size you like. |
| data dictionary | system catalog | The DB2 system
catalog contains metadata in the form of tables and views. The database
manager creates and maintains two sets of system catalog views that
are defined on the base system catalog tables:
|
| data dictionary cache | catalog cache | This is the same concept. |
| data file | container | DB2 data is physically stored in containers, which contain objects. |
| database link | nickname | A nickname is an identifier that refers to an object at a remote data source (a federated database object). |
| dual table | dual table | This is the same concept. |
| dynamic performance views | snapshot monitor SQL administrative views | Snapshot monitor SQL administrative views, which use schema SYSIBMADM, return monitor data about a specific area of the database system. For example, the SYSIBMADM.SNAPBP SQL administrative view provides a snapshot of buffer pool information. |
| extent | extent | A DB2 extent is made up of a set of contiguous data pages. |
| formal parameter | parameter | This is the same concept. |
| global index | nonpartitioned index | This is the same concept. |
| inactive log | online-archive log | This is the same concept. |
| init.ora and Server Parameter File (SPFILE) | database manager configuration file and database configuration file | A DB2 instance can contain multiple databases. Therefore, configuration parameters and their values are stored at both the instance level, in the database manager configuration file, and at the database level, in the database configuration file. These files are managed through the GET or UPDATE DBM CFG command and the GET or UPDATE DB CFG command, respectively. |
| instance | instance or database manager | An instance is a combination of background processes and shared memory. A DB2 instance is also known as a database manager. Because a DB2 instance can contain multiple databases, there are DB2 configuration files at both the instance level (the database manager configuration file) and at the database level (the database configuration file). |
| large pool | utility heap | The utility heap is used by the backup, restore, and load utilities. |
| library cache | package cache | The package cache, which is allocated from database shared memory, is used to cache sections for static and dynamic SQL and XQuery statements on a database. |
| local index | partitioned index | This is the same concept. |
| materialized view | materialized query table (MQT) | An MQT is a table whose definition is based on the results of a query and is meant to be used to improve performance. The DB2 SQL compiler determines whether a query would run more efficiently against an MQT than it would against the base table on which the MQT is based. |
| noarchive log mode | circular logging | This is the same concept. |
| Oracle Call Interface (OCI) | DB2CI Interface | DB2CI is a 'C' and 'C++' application programming interface that uses function calls to connect to DB2 Version 9.7 databases, manage cursors, and perform SQL statements. See IBM Data Server Driver for DB2CI for a list of OCI APIs supported by the DB2CI driver. |
| Oracle Call Interface (OCI) | Call Level Interface (CLI) | CLI is a C and C++ application programming interface that uses function calls to pass dynamic SQL statements as function arguments. In most cases, you can replace an OCI function with a CLI function and relevant changes to the supporting program code. |
| ORACLE_SID environment variable | DB2INSTANCE environment variable | This is the same concept. |
| partitioned tables | partitioned tables | This is the same concept. |
| Procedural Language/Structured Query Language (PL/SQL) | SQL Procedural Language (SQL PL) | SQL PL is an extension of SQL that consists of statements and language elements. SQL PL provides statements for declaring variables and condition handlers, assigning values to variables, and implementing procedural logic. SQL PL is a subset of the SQL Persistent Stored Modules (SQL/PSM) language standard. Oracle PL/SQL statements can be compiled and executed using DB2 interfaces. |
| program global area (PGA) | application shared memory and agent private memory | Application shared memory stores information that is shared between a database and a particular application: primarily, rows of data being passed to or from the database. Agent private memory stores information used to service a particular application, such as sort heaps, cursor information, and session contexts. |
| redo log | transaction log | The transaction log records database transactions and can be used for recovery. |
| role | role | This is the same concept. |
| segment | storage object | This is the same concept. |
| session | session; database connection | This is the same concept. |
| startup nomount | db2start | The command that starts the instance. |
| synonym | alias | An alias is an alternative name for a table, view, nickname, or another alias. The term "synonym" is tolerated and can be specified in place of "alias". Aliases are not used to control what version of a DB2 procedure or user-defined function is being used by an application; to do this, use the SET PATH statement to add the required schema to the value of the CURRENT PATH special register. |
| system global area (SGA) | instance shared memory and database shared memory | The instance shared memory stores all of the information for a particular instance, such as lists of all active connections and security information. The database shared memory stores information for a particular database, such as package caches, log buffers, and buffer pools. |
| SYSTEM table space | SYSCATSPACE table space | The SYSCATSPACE table space contains the system catalog. This table space is created by default when you create a database. |
| table space | table space | This is the same concept. |
| user global area (UGA) | application global memory | Application global memory comprises application shared memory and application-specific memory. |