What is the main benefit of a covering (included-columns) index for a SELECT?

Problem Statement

Explanation

When all needed columns are in the index (keys + included), the plan can avoid extra lookups. This cuts I/O and latency for hot paths. Use includes for non-key columns used in SELECT or WHERE to create index-only scans where supported.

Code Solution

SolutionRead Only

-- SQL Server style
CREATE INDEX ix ON orders(customer_id) INCLUDE (status,total);
-- Postgres: just place columns in index and rely on index-only scan when visible

Practice Sets

This question appears in the following practice sets:

Indexing Strategies & Access Paths

Next Question

Master Interviews
Anywhere, Anytime

What is the main benefit of a covering (included-columns) index for a SELECT?

Problem Statement

Explanation

Code Solution

Practice Sets

Related Questions

Which SQL statement retrieves all columns and rows from a table named employees?

Which clause filters rows before aggregation and affects which rows are grouped?

What is the default sort order when ORDER BY is used without ASC or DESC?

Which construct is commonly used to paginate results in SQL engines like Postgres and MySQL?

Which predicate correctly checks for missing values in standard SQL?

More from SQL & Databases

Master Interviews Anywhere, Anytime

What is the main benefit of a covering (included-columns) index for a SELECT?

Problem Statement

Explanation

Code Solution

Practice Sets

Related Questions

Which SQL statement retrieves all columns and rows from a table named employees?

Which clause filters rows before aggregation and affects which rows are grouped?

What is the default sort order when ORDER BY is used without ASC or DESC?

Which construct is commonly used to paginate results in SQL engines like Postgres and MySQL?

Which predicate correctly checks for missing values in standard SQL?

More from SQL & Databases

Master Interviews
Anywhere, Anytime