Bind File

Enhanced Definition

A bind file is an output generated by a database precompiler (most commonly the DB2 precompiler on z/OS) when processing an application program containing embedded SQL statements. It contains all the SQL statements extracted from the source code, along with information about host variables and program structure, but without the host language logic. Its primary purpose is to serve as input to the DB2 BIND process.

Key Characteristics

- Precompiler Output: It is exclusively created by a DB2 precompiler (e.g., DSNHPC for COBOL/PL/I) during the first phase of compiling an application program with embedded SQL.
- SQL Statement Repository: The file contains all EXEC SQL statements found in the source program, translated into a format understandable by the DB2 BIND utility.
- Input for BIND: A bind file is the essential input for the DB2 BIND command, which creates DB2 packages and plans.
- No Executable Code: It does not contain executable machine code for the application logic; it only represents the SQL portion.
- Platform-Specific: The format and content are specific to the DB2 for z/OS environment and its precompiler.
- Naming Convention: Often named with a .bnd extension or a similar convention to denote its purpose (e.g., MYPROG.BNDFILE).

Use Cases

- Preparing Application Programs: It is a mandatory step in preparing COBOL, PL/I, or C programs with embedded SQL for execution against DB2 for z/OS.
- Creating DB2 Packages and Plans: The bind file is used by the BIND utility to create DB2 packages (collections of DBRMs) and, subsequently, DB2 plans, which are executable access paths for SQL statements.
- Migrating Applications: Bind files can be used to re-bind applications in different DB2 subsystems (e.g., test to production) without needing to re-precompile the original source code.
- Version Control of SQL: Storing bind files in a version control system allows for tracking changes to the embedded SQL logic independently of the application's host language code.

Related Concepts

The bind file is a crucial intermediary between the DB2 Precompiler and the DB2 BIND command. The precompiler processes an application's source code (e.g., COBOL with EXEC SQL statements), replaces the SQL with host language call statements, and simultaneously generates the bind file. This bind file then becomes the input for the BIND utility, which processes it to create DB2 Packages and DB2 Plans, defining how DB2 will execute the SQL statements. Without a bind file, the BIND process cannot occur, and the application cannot interact with DB2.

Best Practices:

Version Control: Always store bind files (or the precompiler options used to generate them) in a version control system alongside the application's source code to ensure traceability and reproducibility.
Consistent Naming: Implement a clear and consistent naming convention for bind files to easily identify the application program and version they correspond to.
Synchronize with Source: Ensure that the bind file used for a BIND operation is always generated from the exact version of the application source code that will be compiled and executed.
Review Precompiler Options: Understand and correctly specify precompiler options (e.g., APOST, QUOTES, SQLFLAG) as they influence the content of the bind file and subsequent BIND behavior.
Automate Generation: Integrate bind file generation into your automated build and deployment pipelines to minimize manual errors and ensure consistency.