Elasticsearch Interview Questions 2026

Design Swiggy's restaurant search and ranking system. How do you index 200k restaurants? Discuss full-text search (Elasticsearch), geospatial filtering, personalised ranking signals (past orders, ratings, delivery time), and how to refresh the index when a restaurant updates its menu.

Design LinkedIn's "People You May Know" feature. How do you compute second and third-degree connections for 900 million users efficiently? Discuss graph storage (adjacency list vs matrix), batch vs real-time computation, and how to refresh recommendations when someone adds a new connection.

Design LinkedIn's job recommendation engine. Given a user's profile, skills, and activity, rank the most relevant open positions. Cover candidate retrieval, feature engineering (skills overlap, company affinity, recency), and how you A/B test ranking changes at scale.

Design LinkedIn's InMail spam filtering system. Premium users can message strangers. How do you detect and block spam campaigns while allowing legitimate cold outreach? Cover: sender reputation, content analysis, and feedback loops.

Design Airbnb's search and availability system. A guest searches for "Paris, 3 nights, 2 guests" and sees ranked listings. Cover: availability calendar storage, real-time inventory updates (when host blocks dates), geospatial search, ranking signals (price, reviews, Superhost status), and how you handle the thundering herd on popular dates.

Design Airbnb's trust and safety system. How do you detect fraudulent listings, scam messages, and fake reviews at scale without blocking legitimate hosts and guests?

Design Flipkart's product search and ranking system. A user searches "wireless earphones under 2000". How do you retrieve, rank, and filter 10,000+ matching products in under 200ms?

Explain Zomato's restaurant onboarding data pipeline. A new restaurant submits menus, photos, and operating hours. How do you validate, normalise, and make this data searchable within minutes of submission?

Design Adobe Experience Cloud's customer data platform. Unify customer profiles from website visits, email clicks, and CRM data across devices and sessions. Cover identity resolution (same person on mobile and desktop), real-time segment computation, and privacy (GDPR right-to-erasure).

Design the search feature for a workspace tool (like Confluence) that indexes millions of documents across thousands of teams, ensuring users only see search results from spaces they have permission to view.