Prefix Cache
Definition
A prefix cache holds computed states of identical input beginnings ready.
A cache of already computed model states for token-identical initial sequences under compatible model and inference configuration.
Simply explained
An already processed identical text beginning is reused under suitable conditions instead of being recomputed.
Why it matters in practice
The term helps to select, develop, evaluate AI systems in a well-founded manner and realistically assess their technical risks.
Example from business
A stable system prompt is reused for multiple requests.
Limits and pitfalls
- Confusing textually similar with token-identical prefixes, not considering configuration changes in the cache key, or overlooking tenant and data isolation.
Origin & history
Prefix caching originated from KV cache reuse for recurring contexts.
Use in mid-sized companies
- Possible application: A stable system prompt is reused for multiple requests.
Frequently asked questions
What does prefix cache mean?
A cache of already computed model states for token-identical initial sequences under compatible model and inference configuration. What mistakes should be avoided? Confusing textually similar sequences with token-identical prefixes, not considering configuration changes in the cache key, or overlooking tenant and data isolation.
Sources
Source checked on 10.10.2026. Editorial application examples are hypothetical; no evidence of real customer results.
Editorially reviewed on: