Distributed relational database on IBM i
Db2® for i provides all the database management functions for IBM® i. Distributed relational database support on the system is an integral part of the operating system, just as is support for communications, work management, security functions, and other functions.
The IBM i operating system can be part of a distributed relational database network with other systems that support a Distributed Relational Database Architecture™ (DRDA) implementation. IBM i can be an application requester (AR) or an application server (AS) in either like or unlike environments. Distributed relational database implementation on the IBM i operating system supports remote unit of work (RUW) and distributed unit of work (DUW). RUW allows you to submit multiple requests to a single database within a single unit of work, and DUW allows requests to multiple databases to be included within a single unit of work.
Using DUW support, you can decrement the inventory count of a part on one system and increment the inventory count of a part on another system within a unit of work, and then commit changes to these remote databases at the conclusion of a single unit of work using a two-phase commit process. Db2 for i does not support distributed requests, so you can only access one database with each SQL statement. The level of support provided in an application program depends on the level of support available on the application server (AS) and the order in which connections and updates are made.
In addition to DRDA access, application requester driver (ARD) programs can be used to access databases that do not support DRDA. Connections to relational databases accessed through ARD programs are treated like connections to unlike servers. Such connections can coexist with connections to DRDA application servers, connections to the local relational database, and connections which access other ARD programs.
On the IBM i operating system, the distribution functions of snapshots and replication are not automatically performed by the system. You can install and configure the DB2® DataPropagator product on IBM i to perform these functions. Also, you can use these functions in user-written application programs. More information about how you can organize these functions in a distributed relational database is discussed in the topic Data availability and protection.
On the IBM i operating system, the distributed request function is not directly supported. However, the DataJoiner product can perform distributed queries, joining tables from a variety of data sources. DataJoiner works synergistically with DataGuide, a comprehensive information catalog in the IBM Information Warehouse family of products. DataGuide provides a graphical user interface to complete information listings about a company's data resources.
The IBM i licensed program includes runtime support for SQL. You do not need the Db2 for i Query Manager and SQL Development Kit licensed program installed on a Db2 for i application requester or application server to process distributed relational database requests or to create an SQL collection on IBM i. However, you need the Db2 for i Query Manager and SQL Development Kit program to precompile programs with SQL statements, to run interactive SQL, or to run Db2 for i Query Manager.
Communications support for the DRDA implementation on the IBM i operating system is provided under either TCP/IP or the IBM Systems Network Architecture (SNA) through the Advanced Program-to-Program Communication (APPC) protocol, with or without Advanced Peer-to-Peer Networking (APPN).