What is a covering index?

Problem Statement

Explanation

If the index contains the filter, join, and select columns, the engine can answer the query from the index alone. That avoids extra lookups and reduces I/O. In some engines you add non-key INCLUDE columns to achieve coverage without bloating the key.

Code Solution

SolutionRead Only

CREATE INDEX idx_orders_customer_date
ON orders(customer_id, order_date)
INCLUDE (total_amount);

Practice Sets

This question appears in the following practice sets:

Indexes & Query Performance Essentials

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What is a covering index?

Problem Statement

Explanation

Code Solution

Practice Sets

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Master Interviews Anywhere, Anytime

What is a covering index?

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