Stored Procedures: Pros, Cons, and Key Concepts for Interviews

Stored procedures are precompiled SQL scripts stored in the database. They allow for executing complex operations directly on the database server. As a backend developer or database engineer, understanding stored procedures is essential for database-heavy applications, and they may come up in interviews. Here’s a comprehensive overview! 🚀

What is a Stored Procedure?

A stored procedure is a set of SQL statements that are saved in the database and can be executed repeatedly. They are designed to encapsulate logic, improve performance, and simplify database operations.

Example (SQL):

CREATE PROCEDURE GetEmployeeById (@EmpId INT)
AS
BEGIN
    SELECT * FROM Employees WHERE EmployeeId = @EmpId;
END;

Executing a Stored Procedure:

EXEC GetEmployeeById 123;

Key Features of Stored Procedures 📜

1. Encapsulation: Encapsulates complex SQL logic into a reusable module.
2. Performance: Precompiled and optimized by the database, reducing runtime query parsing.
3. Security: Can restrict direct access to tables by granting access to the procedure instead.
4. Transaction Management: Allows grouping multiple SQL operations into a single transactional unit.

Advantages of Stored Procedures ✅

1. Improved Performance

• Stored procedures are precompiled and cached in the database server, reducing the overhead of query parsing and execution.

2. Code Reusability

• They allow centralizing logic, which can be reused across multiple applications, reducing code duplication.

3. Security

• Procedures can control access to the database. Users may execute procedures without needing direct table access, protecting sensitive data.

4. Reduced Network Traffic

• Since the logic runs on the database server, only the results are sent back to the application, reducing data transfer.

5. Easier Maintenance

• Centralized logic means updates are done in one place, which simplifies maintaining consistency across applications.

Disadvantages of Stored Procedures ❌

1. Complexity in Debugging

• Debugging stored procedures can be harder than application-level code due to limited tooling and IDE support.

2. Scalability Issues

• Business logic in the database can create bottlenecks as databases scale poorly compared to application servers.

3. Lack of Version Control

• Stored procedures are often outside application version control systems, making it harder to track changes.

4. Increased Database Load

• Placing too much business logic in stored procedures shifts load to the database, potentially overloading it.

5. Portability Issues

• Stored procedures are database-specific, making them harder to migrate between platforms (e.g., SQL Server to MySQL).

When to Use Stored Procedures?

Good Use Cases:

1. Data Processing Tasks:

   • Aggregations, filtering, and data transformations.
   • Example: Generating monthly sales reports.

2. Batch Operations:

   • Performing bulk inserts, updates, or deletes.

3. Enforcing Business Rules:

   • Calculating discounts, taxes, or validation logic directly in the database.

4. Sensitive Data Operations:

   • Access control to protect sensitive data by encapsulating it.

When to Avoid Stored Procedures?

1. Business Logic:

   • Complex business rules are better handled in application code for maintainability and scalability.

2. High Application Scalability:

   • Overusing stored procedures can make databases a bottleneck, whereas application servers scale more effectively.

Stored Procedures vs. Application Logic