Edge Caching vs. Query Caching: Choosing the Right Approach for Scalability

Teams often reach for edge caching to cut latency, and it works well for static or pre-rendered content. But when the bottleneck is the database, not the network, query caching is the solution you need.

Here are a few practical guidelines for choosing the right tool.

• Use edge caching for static or slow-changing responses. It is a good fit for assets, marketing pages, and expensive API responses that can tolerate TTL-based freshness.
• Use edge caching only when responses are deterministic. If the output depends on user identity or fast-changing state, the edge cannot maintain correctness without heavy invalidation logic.
• Use query caching when the database is the constraint. If the primary is CPU-bound, replicas lag, or you repeat the same reads at high volume, caching the SQL work provides far more leverage.
• Use query caching when correctness matters. It can invalidate precisely through transaction awareness, while edge caches rely on TTLs and heuristics.
• Use query caching when your workload generates redundant reads. Collapsing repeated selects removes planner and execution work, which edge caching cannot address.
• Pair both when the boundaries are clear. Use the edge to cut global latency and use query caching to protect database capacity, because they solve different scaling problems.

Edge caching improves delivery by cutting network latency, while query caching increases database headroom by eliminating repeated SQL work. When each layer does the job it is designed for, applications stay fast under load without brittle invalidation logic or oversized infrastructure.

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In Case You Missed It

On December 5, 2025, at PHP Conference Brazil, Bianchi will walk through modern techniques for improving performance and scalability in relational databases using Readyset. If you work with MySQL or PostgreSQL and are battling read bottlenecks, latency, or costly scaling paths, this session will be worth your time. Wagner will show how Readyset operates as a query acceleration layer between your application and database, delivering faster reads without major code changes.

Registration and full conference schedule here.