Why should you care?

Flipkart product list needs id, name, price only — covering index avoids fetching wide rows from heap.

See it live — copy this example

Run in pgAdmin or psql.

CREATE INDEX idx_products_category_cover
ON products (category)
INCLUDE (name, price);

SELECT name, price
FROM products
WHERE category = 'electronics';

What happened?

• category leads the index for filtering.
• name and price sit in leaf pages as payload.
• Planner may choose Index Only Scan if visibility map allows.

Practice next

1. CREATE INDEX with INCLUDE clause.
2. Run EXPLAIN (ANALYZE, BUFFERS) on SELECT.
3. Look for Index Only Scan in plan.
4. Add INCLUDE (status) and select status without heap access.
5. Compare index size with and without INCLUDE columns.

Remember

INCLUDE adds non-key columns to index leaves. Enables index-only scans for covering queries. Keep included columns narrow.

PostgresVerse PLP API

Product listing page hits covering index — 40% fewer buffer reads at peak.

Outcome: CDN cache miss path still fast on origin database.