Progress
DataServer
for ORACLE Guide


The DataServer for ORACLE Logic

The DataServer places Progress equivalents for the data definitions from an ORACLE database into a schema holder. A schema holder contains only data definitions for one or more non-Progress databases. When you issue 4GL statements, they are compiled into calls to the ORACLE database. When the Progress client executes 4GL statements and retrieves information from the ORACLE database, it relies on data definitions maintained by the data dictionary in the Progress schema holder. Figure 1–2 shows the internal logic of the DataServer for ORACLE.

Figure 1–2: The DataServer for ORACLE Logic

The DataServer uses the ORACLE PRO*C OCI (ORACLE Call Interface) to access an ORACLE instance. An ORACLE instance provides the software mechanisms for accessing and controlling a database. When you start up the ORACLE Database Manager (DBMS) against a database, you create an ORACLE instance. See your ORACLE documentation for more information on instances.

When you execute a Progress application that accesses an ORACLE database, the Compiler translates the 4GL statements in the Progress application into their SQL equivalents. The DataServer then issues the SQL statements to the ORACLE instance through the OCI. The ORACLE instance processes the SQL statements and returns the results to Progress through the OCI.

You can also send SQL statements directly to ORACLE. The DataServer passes SELECT SQL statements that you reference in a 4GL application directly to ORACLE without translating them. The DataServer also allows you to issue PL/SQL statements from a Progress application. See the "Sending SQL Statements" section in "Programming Considerations," for more information.


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