[Solved] What is the main benefit of a covering index in a database? — Ans: It contains all columns needed by a query, avoiding table lookups. | SQL

SQL - Indexes and Query Performance

What is the main benefit of a covering index in a database?

AIt contains all columns needed by a query, avoiding table lookups.

BIt compresses data to save disk space.

CIt automatically backs up the database.

DIt encrypts data for security.

Step-by-Step Solution

Solution:

Step 1: Understand what a covering index stores
A covering index includes all columns that a query needs, so the database can get results from the index alone.
Step 2: Identify the benefit of avoiding table lookups
By not accessing the main table, queries run faster because less data is read and fewer disk operations occur.
Final Answer:
It contains all columns needed by a query, avoiding table lookups. -> Option A
Quick Check:
Covering index = all needed columns [OK]

Quick Trick: Covering index has all query columns, no table needed [OK]

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