Unverified50% confidenceFactExact time
Prefix caching depends on strict conditions: the reused portion must be identical from the very first token of the sequence, otherwise the cache is invalidated and the entire segment is recomputed.
1
Sources
50%
Confidence
Long-term
Relevance
10/19/2026
First Seen
Sources
Related Entities
Related Claims
UnverifiedWhether prompt caching hits depends on byte-for-byte consistency of the request prefix; if even one character at the beginning differs, the entire cache is invalidated.75% similarUnverifiedPrompt caching takes effect in units of "prefix" and only works for content that is completely identical from the start; once a token in the middle changes, the content after it cannot hit the existing cache.72% similarUnverifiedPrompt Caching supports only prefix matching, and only repeated content placed at the very front can be reused; in engineering practice one should follow the principle of fixed content first and dynamic content last.71% similarPartially VerifiedIn Anthropic's API billing system, prompt caching allows a stable prefix to be marked as cached content, and subsequent identical prefixes directly reuse the KV without recomputing attention, with these tokens recorded as "cache reads".70% similarUnverifiedPrompt Caching requires the prompt to meet a minimum cacheable length (typically 1024 tokens for Anthropic), and the prefix must be byte-for-byte identical for the cache to hit.69% similar
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