Oracle APEX, a low-code development platform seamlessly integrated with the Oracle Database, is a phenomenal tool for rapidly building robust web applications. But what if your enterprise utilizes PostgreSQL alongside or instead of an Oracle Database? The good news is that you can seamlessly integrate PostgreSQL’s robust features into your Oracle APEX applications.

Why Connect Oracle APEX to PostgreSQL?

• Legacy Systems: Your organization might have valuable data stored in legacy PostgreSQL databases that you’d like to leverage within modern APEX applications.
• Flexibility: PostgreSQL offers unique features or data structures that better fit specific projects than Oracle Database’s offerings.
• Cost considerations: PostgreSQL may provide attractive cost advantages for specific use cases.

Methods of Integration

Let’s explore the primary ways you can achieve this powerful combination:

1. Database Links:

• • Establish database links in your Oracle database that point to your PostgreSQL database.
  • Create views, synonyms, or materialized views in Oracle that query and manipulate data directly from PostgreSQL tables.
  • Build APEX pages and forms based on these views as you would with any Oracle-based objects.

1. REST APIs:

• • Develop RESTful web services within PostgreSQL using technologies like PostgREST or build custom APIs using frameworks like Python’s Flask or Django.
  • Configure APEX as a REST client that consumes these APIs, allowing you to fetch, insert, update, and delete data in your PostgreSQL system.

Example: Creating a Read-Only APEX Report on PostgreSQL Data

1. Database Link Setup: Ask your database administrator to establish a database link from Oracle to your PostgreSQL database.
2. Create a View in Oracle:
3. SQL
4. CREATE VIEW employees_vw AS
5. SELECT employee_id, first_name, last_name, salary
6. FROM employees@postgresql_dblink; 
7. Use code with caution.
8. content_copy
9. Build the APEX Report:

• • Navigate to the APEX App Builder.
  • Create a new report page.
  • Select ‘Interactive Report’ as the report type.
  • Set the source as ‘SQL Query’ and input the following: SELECT * FROM employees_vw

Additional Considerations

• Performance: Queries involving data transfer between databases might impact performance. Optimize these queries and consider caching techniques where applicable.
• Security: Secure database links and REST APIs using robust authentication and encryption.

Conclusion

• By bridging the gap between Oracle APEX and PostgreSQL, you gain tremendous flexibility in architecting your applications while leveraging both technologies’ strengths. Experiment with these techniques to expand the reach and capabilities of your APEX applications.