Your RAG app is only as current as its index

Your RAG app is only as current as your index. Most teams find out when a customer quotes a policy that was replaced months ago.

Freshness is a pipeline problem, not a prompt problem. A few habits that keep an index honest:

1. 1Index incrementally. Re-embed only the documents that changed, using a content hash or a last-modified time, instead of rebuilding everything.
2. 2Handle deletes. A deleted or replaced document must leave the index. Orphan chunks are how old answers keep coming back.
3. 3Store dates on every chunk: when it was created and when it was last verified. Show the date in the answer.
4. 4Prefer newer versions when two chunks conflict, or at least tell the user there are two.
5. 5Monitor the lag. Track how long a change takes to show up in answers, and alert when it grows.

Cached answers need the same care. If you cache responses, invalidate them when their source chunks change.

A quick test: edit one document today. How long until the app answers with the new text? If you don't know, that's the first thing to measure.

How long does it take a change in your source documents to reach your users?