[Solved] What is wrong with this query if the goal is to optimize it using an index?SELECT * FROM employees WHERE salary * 1.1 > 50000; | PostgreSQL

PostgreSQL - Performance Tuning

What is wrong with this query if the goal is to optimize it using an index?
SELECT * FROM employees WHERE salary * 1.1 > 50000;

AThe query lacks an ORDER BY clause

BThe multiplication operator is invalid in WHERE clause

CThe query should use HAVING instead of WHERE

DThe expression salary * 1.1 prevents index usage on salary

Step-by-Step Solution

Solution:

Step 1: Check expression on indexed column
Using salary * 1.1 changes the column value, so index on salary is not used.
Step 2: Understand index usage rules
Indexes work on raw column values; expressions require special indexes.
Final Answer:
The expression salary * 1.1 prevents index usage on salary -> Option D
Quick Check:
Expressions on indexed columns block index use [OK]

Quick Trick: Avoid expressions on indexed columns in WHERE [OK]

Common Mistakes:

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What is wrong with this query if the goal is to optimize it using an index?