Provide some kind of API to invalidate the cache

[aturki]

From what I understand, the cache invalidation relies only on a TTL. When the original data in a RAG pipeline changes frequently, we might end up working with stale data. Any plans to add support for cache invalidation please 🙏 ?

[messkan]

Thanks for the question 🙏

You’re right to be concerned about stale data in fast-moving RAG pipelines.

At the moment, PromptCache relies on TTL for automatic expiration, but it also supports explicit cache deletion (manual invalidation). This allows applications to actively purge cache entries when the underlying RAG data changes.

We intentionally don’t infer invalidation automatically from data changes, since this logic is highly application-specific in RAG setups and hard to generalize safely.

We’ll document this behavior more clearly and add examples (TTL vs manual cache deletion in RAG scenarios) in the next release.

More advanced invalidation mechanisms (e.g. tag/namespace-based invalidation) are on the roadmap, but not implemented yet.

Thanks again for the feedback — it helps improve both the product and the docs 👍