🚀 Lead Backend Engineer Interview Tool

Database Sharding Interview

Ace your lead backend engineer database sharding interview with our AI-powered real-time coach. Get instant guidance on sharding strategies, data partitioning, distributed database architecture, and scaling techniques.

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Social Media Platform Database Sharding

Interviewer [00:00:05]: Design a database sharding strategy for a social media platform with 500 million users and 10 billion posts.

You [00:00:15]: I'd like to start by understanding the access patterns and requirements better. What are the main entities and relationships? What are the most common queries? And what are the performance and availability requirements?

Interviewer [00:00:28]: Good questions. The main entities are users, posts, comments, and likes. The most common queries are fetching a user's feed (posts from people they follow), viewing a user's profile with their posts, and searching for content. We need sub-100ms response times for feed generation and high availability with regional failover.

AI Suggestion:

Sharding Approach: Propose horizontal sharding with a combination of strategies
User Data Sharding: Suggest hash-based sharding on user_id with consistent hashing
Post Data Sharding: Recommend a composite strategy:
- Primary sharding by user_id (author) for write distribution
- Secondary indices for efficient feed generation
- Time-based partitioning for historical data
Cross-Shard Queries: Discuss fan-out approach for feed generation with caching
Rebalancing Strategy: Explain virtual nodes and incremental rebalancing
Global Indices: Mention distributed search service for content discovery
Data Consistency: Discuss read-after-write consistency challenges and solutions

🔄 Sharding Strategy Design

Get expert guidance on designing effective database sharding strategies, including hash-based, range-based, and geography-based approaches with real-time suggestions tailored to your specific interview scenario.

⚡ Distributed Query Optimization

Receive instant recommendations on optimizing queries across sharded databases, including cross-shard joins, aggregations, and transaction management with practical implementation details.

📊 Shard Key Selection Expertise

Access real-time guidance on selecting optimal shard keys based on data access patterns, query requirements, and data distribution to ensure balanced load and minimize cross-shard operations.

🔍 Rebalancing & Migration Strategies

Get instant suggestions for shard rebalancing approaches, data migration techniques, and online schema changes that maintain availability while redistributing data across shards.

🔒 Consistency & Transaction Management

Receive guidance on maintaining data consistency across shards, implementing distributed transactions, and handling cross-shard integrity constraints in various database technologies.

📈 Scaling & Performance Optimization

Access expert advice on vertical vs. horizontal scaling decisions, read/write splitting strategies, and performance optimization techniques specific to sharded database architectures.