Distributed Relational Database Architecture
With Distributed Relational Database Architecture ( DRDA ), both the IBM architecture for distributed databases referred to, which are located on different heterogeneous platforms, as well as developed by IBM for the distribution of the data protocol.
DRDA enables distributed access to the various versions of the IBM database systems DB2 and Informix .
There are different stages in the implementation of the DRDA:
- Remote request
- Support of a single SQL request on a remote system
- You can only refer to one location.
- No transaction processing is supported.
- Each statement is processed separately and executed immediately
- The server executes a COMMIT after each statement.
- Remote Unit of Work (RUW)
- Support of multiple SQL requests within one unit of work
- Only one server is addressed within a unit of work
- The one-phase commit is still sufficient
- Distributed Unit of Work (DUW)
- Several servers can be addressed within a unit of work
- A single request addresses only one server
- Use of two-phase commit required
- Distributed Request (DR)
- Several servers can be addressed in one query (one SQL statement)
In the DB2 world, DUW and even DR are mostly possible.
If servers from other database manufacturers or ODBC data sources are to be accessed, then in some cases only levels 1 or 2 are possible.