Dos and Don'ts for Building Efficient Oracle PL/SQL Applications

Oracle PL/SQL is a powerful language used extensively for database programming within Oracle environments. As an Oracle PL/SQL developer, building efficient applications isn’t just about writing code that works; it's about writing code that performs optimally, is maintainable, and scales effectively. Here, we dive into essential dos and don'ts to help enhance your application's performance and maintainability.

1. Do Use Bulk Collect and ForAll

When it comes to handling large datasets, PL/SQL provides mechanisms like Bulk Collect and ForAll to enhance performance. These features allow you to move data between SQL and PL/SQL with fewer context switches, which can greatly speed up operations.

• Bulk Collect: Allows fetching of multiple rows from a query into a PL/SQL collection in a single context, minimizing memory usage and improving performance.
• ForAll: Used for executing DML operations efficiently by minimizing parse time and increasing array DML execution speed.

2. Don't Overlook Indexes

Indexes are crucial for improving query performance. However, they must be used wisely:

• Ensure indexes are used on frequently queried columns to speed up search operations.
• Avoid creating too many indexes on a single table as it can lead to performance overhead during DML operations.
• Regularly monitor and maintain indexes. Use the Oracle automated tools like SQL Access Advisor for recommendations.

3. Do Optimize PL/SQL Loops

Loops are a fundamental part of programming but can be a performance bottleneck if not used properly.

• Minimize the work done inside loops. Consider moving queries outside of loops if results are invariant.
• Use collections to handle data instead of cursors where possible, reducing the number of times you need to interact with the database.

4. Don't Ignore Exception Handling

Ignoring exception handling can lead to software crashes and data inconsistencies. Implement robust exception handling to anticipate and manage errors gracefully.

• Utilize EXCEPTION blocks to catch and handle known exceptions.
• Avoid blanket catch-all exception handlers as they can obscure actual errors.

5. Do Decompose Complex Queries

Decomposing complex queries into simpler parts can make them more readable and maintainable.

• Break down extensive queries into manageable subqueries or views.
• Decomposition can also help identify specific performance bottlenecks within the query.

6. Don't Hard Code Values

Hard-coding values can make your application inflexible. Instead:

• Use bind variables. They improve the reusability of SQL statements and help Oracle perform execution plan reuse.
• Externalize configuration values to parameters.

7. Do Regularly Refactor Code

Refactoring code is an essential practice for maintaining a clean codebase and improving performance:

• Simplify logic and remove unnecessary redundancies.
• Improve structure by adhering to naming conventions and best practices.

8. Don't Forget to Document

Comprehensive documentation is crucial for knowledge transfer and ease of maintenance:

• Comment your code extensively, explaining the function and purpose of complex blocks.
• Maintain documentation for schema designs, API interfaces, and module purposes.

9. Do Test Extensively

Testing is non-negotiable for quality assurance in software development:

• Conduct unit testing, integration testing, and performance testing rigorously.
• Write test scripts to automatically verify the expected outcomes for your PL/SQL scripts and modules.

10. Don't Neglect Database Tuning

Effective database tuning can drastically improve application performance. Pay attention to:

• Execution plans and statistics provided by Oracle's AWR and SQL Tuning Advisor.
• Ensure periodically purging of logs and unnecessary data to keep the database lean.

Conclusion