Performance Tuning with Subquery Factoring and Inline Views

Speed Up Complex Queries: Using Subquery Factoring and Inline Views in Oracle SQL

Overview: Discuss how subquery factoring (WITH) and inline views help break down complex logic, reduce repeated computations, and improve readability and performance. Touch on materialization hints if needed. Example Query:

WITH top_performers AS (
    SELECT employee_id, salary, department_id
    FROM employees
    WHERE salary > 10000
)
SELECT 
    d.department_name,
    tp.employee_id,
    tp.salary
FROM 
    top_performers tp
JOIN 
    departments d ON tp.department_id = d.department_id;

Use Case: Optimize queries that reuse subsets of data (e.g., high-salary employees) and reduce redundancy.