OpenSearchCon Europe 2026

Caching is essential for achieving low latency and high throughput in search systems, yet it’s often misunderstood or misused. OpenSearch and Lucene provide multiple caching layers—such as the request cache, field data cache, and Lucene query cache—each designed for different workloads and access patterns.

In this talk, we break down how OpenSearch caches work, when they help, and common pitfalls that lead to low hit rates or wasted memory. We share lessons from real production systems, showing how tuning, architectural choices, and benchmark-driven evaluation improve cache effectiveness, performance, and resiliency.

We then discuss optimizations across key cache layers — the request cache, field data cache, and Lucene query cache — and the impact they have on real workloads.

Finally, we introduce tiered caching, when it makes sense, how it integrates with existing cache layers, and the trade-offs involved.

This session is intended for engineers who want a practical understanding of caching in OpenSearch and Lucene and actionable guidance for improving search performance in production.