The HiRDB External Data Access facility allows you to access, through the HiRDB interface, multiple database tables built by DBMSs on various types of machines, including those built with third party products. It even allows you to view and update in a single table information stored in different types of databases (if you are using a foreign table or a view table). This facility is called the HiRDB External Data Access facility. Figure 2-1 provides an overview of the HiRDB External Data Access facility. For details about the HiRDB External Data Access facility, see the HiRDB External Data Access Version 7 Description and User's Guide.

Figure 2-1 Overview of the HiRDB External Data Access facility

Explanation

You can view and update external DBMS databases from a HiRDB client. An external DBMS is called a foreign server.

A table that can be viewed or updated with the HiRDB External Data Access facility is called a foreign table. A foreign table is a table defined on HiRDB based on the definition information for a table on a foreign server. A foreign table is required in order to view or update tables in foreign servers. Note that HiRDB manages only the definition information for the table; the foreign server manages the actual content of the table.

HiRDB External Data Access provides the following features:

• Ability to view and update in a single table database information derived from multiple DBMSs in different locations
• Ability to access tables using only the HiRDB interface, even in environments running multiple DBMSs

You can expect the following benefits when you use HiRDB External Data Access:

• Reduction in development times and operation costs through the use of legacy assets
• Flexible support for modification and expansion of database environments
• Simplification of application development through use of the HiRDB interface (SQL interface)
• Improvement in the ability to efficiently deploy information resources through realization of on-demand access
• Ability to provide the latest information available

The following lists the DBMSs that HiRDB can connect to as a foreign server:

• HiRDB (HiRDB Version 5.0 05-06 or later)^*
• XDM/RD E2 06-00 or later
• ORACLE (Oracle 8i 8.1.7)
• ORACLE (Oracle 9i 9.2)
• ORACLE (Oracle 10g 10.1)

*

• An instance of HiRDB connected to as a foreign server is called a foreign HiRDB.
• Both HiRDB/Single Server and HiRDB/Parallel Server can be used as foreign servers.
• Neither the Linux version nor the Windows version of HiRDB version 5.0 can be used as a foreign server.

You must have a back-end server to connect to a foreign server (in order to view or update a foreign table). Such a back-end server is referred to as a back-end server for connecting to foreign servers (or a back-end server for viewing or updating foreign tables). On the HiRDB side, you also need the products shown in Table 2-1.

Table 2-1 Products needed on the HiRDB side to use the HiRDB External Data Access facility

Product name	Description
HiRDB External Data Access	Needed to execute the HiRDB External Data Access facility.
HiRDB External Data Access Adapter	Handles the interface differences between HiRDB and the connection-target DBMS. A HiRDB External Data Access Adapter is available for ORACLE . Because HiRDB Data Access Adapter is included in HiRDB External Data Access, you do not need a separate HiRDB External Data Access Adapter when the connection-target DBMS is either HiRDB or XDM/RD E2.
ORACLE client product	Needed when the connection-target DBMS is ORACLE.

Figure 2-2 shows an example of a system configuration when the HiRDB External Data Access facility is being used.

Figure 2-2 System configuration example when the HiRDB External Data Access facility is being used

1

Back-end server for connecting to foreign servers

2

• If the foreign server is ORACLE, you need a HiRDB External Data Access Adapter for ORACLE.
• If the foreign server is HiRDB or XDM/RD E2, you do not need HiRDB External Data Access Adapter. The HiRDB External Data Access Adapter functionality is included in HiRDB External Data Access.

3

• If the foreign server is ORACLE, you need the ORACLE client product.
• If the foreign server is HiRDB or XDM/RD E2, you need a HiRDB client. However, the HiRDB server includes the HiRDB client functionality, which means that you do not need to install a HiRDB client.

For details about the products you need when using the HiRDB External Data Access facility, see the HiRDB External Data Access Version 7 Description and User's Guide.