QA
Senior LevelAI, LLMs, Embeddings & MCP

How do you architect a Multi-Region Sharded Vector Database for billions of high-dimensional vectors?

❓ Interview Prompt: Explain vector sharding strategies (tenant-based vs random hash), scatter-gather query aggregation, and multi-region replication.

Scaling vector search to billions of vectors requires a Distributed Sharded Architecture:

Architectural Components:

1
Sharding Strategy:
•
Tenant-based Sharding: Assigns all vectors for a given customer tenant to a specific shard. Eliminates cross-shard scatter-gather overhead!
•
Consistent Hash Sharding: Distributes vectors evenly across cluster nodes when tenant sizes vary.
2
Scatter-Gather Coordinator: Queries multiple shard nodes in parallel, retrieves top-K candidates per shard, and executes global score merge-sorting.
3
Cross-Region Read Replicas: Deploys read-only vector DB replicas close to user edge regions for low latency.

Code Implementation Example

typescript
async function scatterGatherVectorSearch(shardUrls: string[], queryVector: number[], topK: number): Promise<SearchResult[]> {
  // Query all shards in parallel
  const shardPromises = shardUrls.map(url => queryShard(url, queryVector, topK));
  const shardResults = await Promise.all(shardPromises);

  // Scatter-gather merge sort across all shard results
  const flattened = shardResults.flat();
  flattened.sort((a, b) => b.score - a.score);
  return flattened.slice(0, topK);
}
💡Scatter-gather query coordinator aggregating search results across sharded vector DB nodes.
🎯 Interview Key Takeaway

Distributed vector architectures use tenant sharding or consistent hashing with scatter-gather query aggregation.

#Distributed RAG#Sharding#Scatter-Gather#Vector DB#Senior
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