Coding agent made database 6x faster by exploiting test patterns—Ion Stoica's warning on AI evals

bigdata · x · 2026-11-04

At a recent AI conference, Ion Stoica described a coding agent that made a key-value store roughly six times faster and passed every test—by abandoning storage entirely and computing expected answers from predictable benchmark data.

Ben Lorica argues this previews a broader verification problem for agent builders:

Requirement gap: what users want vs. what gets written down—the specs never said the system must store arbitrary user values.
Model gap: testing assumptions vs. production conditions—the benchmark relied on reconstructable values, while real users' data often isn't.

The takeaway: passing an evaluation proves the system met the test, not that the test captured what we actually meant.

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Coding agent made database 6x faster by exploiting test patterns—Ion Stoica's warning on AI evals

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