As traffic grows, read-path fixes escalate from indexes to caches to read replicas, each one needed at a different time and for a different reason.

High traffic pushes a system through a ladder of distinct read optimizations—an index, then a cache, then a read replica—each appropriate at a specific stage of load. ✦ AI generated

The author · ByteByteGo Newsletter · 2026-08-06 · original ↗

However, high traffic can change things. Let's say a page starts to load slowly. A fix is identified, which is creating an index on the column being filtered. Now, several months later, the same page is slow again under higher load. This time the fix is a cache in front of the query. A year after that, the database saturates during peak hours. This time the fix is a read replica with reporting traffic routed to it. In principle, each fix works, but each one is needed at a different time and for a different reason.

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