Upgrading embedded SQL applications

Upgrading your existing embedded SQL applications to Db2® version 12.1 involves managing the changes between Db2 version 12.1 and previous releases that impact these applications and verifying that these applications function as expected.

Before you begin

• Ensure that you have access to a Db2 version 12.1 server, including instances and databases. The Db2 server can be part of a testing environment.
• Ensure that the C, C++, COBOL, FORTRAN, or REXX development software is at a version level that is supported by Db2 database products.
• Perform previous steps in the upgrading database applications task.

Restrictions

This procedure only applies to database applications programmed in C, C++, COBOL, FORTRAN, and REXX.

To upgrade your embedded SQL applications to Db2 version 12.1:

1. If you modified the library path environment variables, ensure that those variables include the correct Db2 shared library path for your applications . The environment variables listed in this table specify additional paths to enable your applications to find the appropriate Db2 shared library at runtime (in most cases).

   On the Linux® operating system: if you link an application using the RPATH link option without also specifying the RUNPATH link option, the LD_LIBRARY_PATH environment variable will be ignored at application run time, which can cause your application to fail.

2. Test your embedded SQL applications in a Db2 version 12.1 testing environment. If testing is successful, you do not need to perform any additional steps.
3. If you bound your embedded applications using the BIND command with the BLOCKING ALL or BLOCKING UNAMBIGIOUS clause to enable the blocking of cursors for LOB columns, ensure that the instance_memory or database_memory database configuration parameters are set to AUTOMATIC or increase their numeric value to account for the extra memory usage. If you cannot increase these database configuration parameters, you have the following options:
   • Rebind them using the BIND command specifying BLOCKING NO or precompile them using the PRECOMPILE command specifying the SQLRULES STD command parameter. The BLOCKING NO clause disables blocking of all cursors in the application. The SQLRULES STD command parameter might have other effects than disabling blocking cursors.
   • Modify the application source code and declare the cursor with the FOR UPDATE clause to disable blocking.
4. To explicitly specify the correct Db2 shared library path for your applications, do one of the following:

   • If the application source code is available, rebuild the application. Specify the required Db2 shared library path. This is the best option.

   • Create a wrapper script to run your application. In the wrapper script, explicitly set the library path environment variable to the required Db2 shared library path.

   • If you do not have the original source code available, run the db2chglibpath command to update the embedded runtime library path within the binary code of your application. This command is provided as-is and should therefore be considered a last resort.

What to do next

After upgrading your embedded SQL applications, perform the remaining steps in the upgrading database applications task.