The owner of DD basic tables and views is OTGDB2. This cannot be changed.

The SUBSTR function can be used with the Oracle database in ways that are not compatible with a DRDA server, such as DB2 UDB for z/OS.

Therefore, the SUBSTR function is post-processed. However, it is possible to allow the server to process it natively using the Native Semantics feature. Refer to Developing Applications, for details.

Data type limitations with Oracle Database Gateway for DRDA.

Refer to DRDA Data Type to Oracle Data type Conversion for detailed information about data types. 

Null values are not passed into, or returned from, calls to stored procedures through the gateway.

DB2 Universal Database does not support string concatenation of numbers.

For example, the following is not allowed:

SELECT 2||2 FROM table@dblink

If GLOBAL_NAMES is set to TRUE in the Oracle database INIT.ORA file, then in order to be able to connect to the gateway, you must specify the Heterogeneous Services (HS) initialization parameter, HS_DB_DOMAIN, in the Gateway Initialization Parameter file to match the value of the DB_DOMAIN parameter of the Oracle database.

Refer to Oracle Database Gateway Installation and Configuration Guide for IBM AIX on POWER Systems (64-Bit), Linux x86-64, Oracle Solaris on SPARC (64-Bit), Oracle Solaris on x86-64 (64-Bit) and HP-UX Itanium or Oracle Database Gateway Installation and Configuration Guide for Microsoft Windows, depending on your platform, for more information.

The gateway utilizes a package for statement execution. This package is implicitly bound the first time the gateway connects to the target DB2 system.

Ensure that the user ID connecting to the DB2 system has the necessary privileges to bind a package. Refer to Oracle Database Gateway Installation and Configuration Guide for IBM AIX on POWER Systems (64-Bit), Linux x86-64, Oracle Solaris on SPARC (64-Bit), Oracle Solaris on x86-64 (64-Bit) and HP-UX Itanium or Oracle Database Gateway Installation and Configuration Guide for Microsoft Windows, depending on your platform, for more information.

DB2 does not allow number addition or subtraction with date data types.

In general, the following types of SQL expression forms do not work correctly with the gateway because of DB2 limitations:

date + number
number + date
date - number
date1 - date2

The date and number addition and subtraction (date + number, number + date, date - number) forms are sent through to the DB2 where they are rejected.

Also, DB2 does not perform date subtraction consistently. When you subtract two dates (date1 - date2), differing interpretations of date subtraction in DB2 cause the results to vary by server.

Because of a restriction of the DRDA architecture, rows with aggregate length exceeding 32 KB in DRDA representation cannot be stored or retrieved.

SQL*Plus cannot fetch columns with the LONG data type from the Oracle Database Gateway for DRDA.

IBM DB2 has introduced a feature called Commit on Return for stored procedures.

This feature allows DB2 to perform an automatic commit after a stored procedure runs successfully. This feature is enabled when the procedure is created. To ensure data integrity, the Oracle Database Gateway for DRDA does not support this feature in a heterogeneous environment. When attempting to call a stored procedure that has this feature enabled, through the gateway, the gateway will return an error, ORA-28526 or PLS-00201 (identifier must be declared).

The DB2 ROWID column is not compatible with the Oracle ROWID column.

Because the ROWID column is not supported, the following restrictions apply:

• UPDATE and DELETE are not supported with the WHERE CURRENT OF CURSOR clause. To update or delete a specific row through the gateway, a condition style WHERE clause must be used. (Bug No. 205538)

  When UPDATE and DELETE statements are used in precompiler and PL/SQL programs, they rely internally on the Oracle ROWID function.

• Snapshots between Oracle database and DB2 are not supported.

  Snapshots rely internally on the Oracle ROWID column.

Oracle bind variables become SQL parameter markers when used with the gateway.

Therefore, the bind variables are subject to the same restrictions as SQL parameter markers.

For example, the following statements are not allowed:

WHERE :x IS NULL 
WHERE :x = :y 

Oracle Database Gateway for DRDA does not support CONNECT BY in SELECT statements.