---
title: "query covering indexes"
description: "Covering indexes include all columns needed by a query, enabling index-only scans that skip the table entirely."
type: skill
canonical_url: https://claudary.paisolsolutions.com/skills/query-covering-indexes
source: "Claudary"
difficulty: intermediate
author: "Claude Code Knowledge Pack"
date: 2026-07-10T11:37:22.807Z
license: CC-BY-4.0
attribution: "query covering indexes — Claudary (https://claudary.paisolsolutions.com/skills/query-covering-indexes)"
---

# query covering indexes
Covering indexes include all columns needed by a query, enabling index-only scans that skip the table entirely.

## Overview

---
title: Use Covering Indexes to Avoid Table Lookups
impact: MEDIUM-HIGH
impactDescription: 2-5x faster queries by eliminating heap fetches
tags: indexes, covering-index, include, index-only-scan
---

## Use Covering Indexes to Avoid Table Lookups

Covering indexes include all columns needed by a query, enabling index-only scans that skip the table entirely.

**Incorrect (index scan + heap fetch):**

```sql
create index users_email_idx on users (email);

-- Must fetch name and created_at from table heap
select email, name, created_at from users where email = 'user@example.com';
```

**Correct (index-only scan with INCLUDE):**

```sql
-- Include non-searchable columns in the index
create index users_email_idx on users (email) include (name, created_at);

-- All columns served from index, no table access needed
select email, name, created_at from users where email = 'user@example.com';
```

Use INCLUDE for columns you SELECT but don't filter on:

```sql
-- Searching by status, but also need customer_id and total
create index orders_status_idx on orders (status) include (customer_id, total);

select status, customer_id, total from orders where status = 'shipped';
```

Reference: [Index-Only Scans](https://www.postgresql.org/docs/current/indexes-index-only-scans.html)

---

Source: [Claudary](https://claudary.paisolsolutions.com/skills/query-covering-indexes) · https://claudary.paisolsolutions.com