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Oracle – 28 – External Procedures

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External procedures in Oracle refer to a feature that allows you to execute code written in a programming language other than PL/SQL within the Oracle database. These external procedures provide a way to integrate and execute code written in languages like C, C++, or Java as part of your database applications. Here’s a brief description of Oracle external procedures:

1. Integration of Non-PL/SQL Code:

  • External procedures enable the integration of code written in languages other than PL/SQL into your Oracle database environment. This can be particularly useful when you need to incorporate low-level system operations, complex algorithms, or specialized libraries that are not readily available in PL/SQL.

2. Supported Languages:

  • Oracle supports several languages for creating external procedures, including C, C++, and Java. You can write your code in one of these languages and invoke it from PL/SQL as an external procedure.

3. Shared Libraries:

  • External procedures are typically implemented as shared libraries or dynamic link libraries (DLLs) in the case of Windows environments. These libraries contain the compiled code written in the chosen programming language.

4. External Procedure Call Specification:

  • To use an external procedure, you define a call specification in the Oracle database. The call specification specifies the external procedure’s name, input parameters, and return values.

5. Calling External Procedures:

  • From PL/SQL code, you can call external procedures as if they were regular PL/SQL procedures or functions. You invoke them using the call specification, passing any required parameters.

6. Data Exchange:

  • You can exchange data between PL/SQL and external procedures by passing parameters. External procedures can take input parameters from PL/SQL and return results or modified data to PL/SQL.

7. Security and Privileges:

  • To use external procedures, you need the appropriate privileges to execute the code. External procedures execute with the privileges of the Oracle database user who invokes them, so security considerations are essential.

8. Performance Considerations:

  • External procedures can be used to offload computationally intensive tasks to lower-level languages, potentially improving performance. However, it’s essential to carefully design and optimize the external code to minimize performance overhead.

9. Debugging and Testing:

  • Debugging and testing external procedures may require specialized tools and techniques, as the code is executed outside the PL/SQL environment. You’ll need to use tools specific to the programming language in which the external code is written.

10. Platform Compatibility:

  • External procedures may require platform-specific code or libraries. Ensure that the external code is compatible with the operating system and hardware architecture of your Oracle database server.

Oracle external procedures provide a way to extend the functionality of your database applications by leveraging code written in other programming languages. While they offer flexibility and the ability to perform tasks that are challenging in PL/SQL, they also introduce complexity, especially in terms of security, debugging, and platform compatibility. Therefore, using external procedures should be carefully planned and executed to ensure that they meet the specific needs of your application.