---
title: "RAG Is Blind to Time — I Built a Temporal Layer to Fix It in Production"
url: https://daily.dev/posts/rag-is-blind-to-time-i-built-a-temporal-layer-to-fix-it-in-production-n1qi1u6py
source_url: https://towardsdatascience.com/rag-is-blind-to-time-i-built-a-temporal-layer-to-fix-it-in-production
type: article
source: "Towards Data Science"
published: 2026-05-09T13:56:50.519Z
updated: 2026-05-09T13:57:25.023Z
tags: ["python", "rag", "vector-search"]
reading_time: 24
upvotes: 1
comments: 0
language: en
---

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# RAG Is Blind to Time — I Built a Temporal Layer to Fix It in Production

**[Towards Data Science](https://daily.dev/sources/tds)** · 24 min read · 1 upvotes · 0 comments

## Summary

Standard RAG systems rank documents by cosine similarity with no awareness of when information was true, causing outdated documents to surface ahead of current ones. This post describes a temporal reranking layer inserted between the vector retriever and the LLM that addresses three distinct time problems: hard-removing expired facts, boosting active time-bounded events, and using exponential decay to prefer newer versions of updated documents. The design uses two orthogonal axes — validity state (EXPIRED/VALID/TEMPORAL) and document kind (STATIC/VERSIONED/EVENT) — combined in a scoring formula that blends semantic similarity with decay score, recency score, validity multiplier, and an event relevance gate. Content-type-specific half-life profiles (from 1 day for breaking news to 36,500 days for mathematics) prevent over-penalizing timeless content. Additional features include document pairing for weak-but-useful sources, confidence tiers for conflicting documents, query-adaptive temporal weighting, and version-chain deduplication. The implementation adds 15–30ms overhead and requires only a created_at timestamp on documents. Full code is available on GitHub.

## Full article

daily.dev links to this article rather than hosting it. Read it at the original source: <https://towardsdatascience.com/rag-is-blind-to-time-i-built-a-temporal-layer-to-fix-it-in-production>

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---

Tags: [#python](https://daily.dev/tags/python), [#rag](https://daily.dev/tags/rag), [#vector-search](https://daily.dev/tags/vector-search)

[View this post on daily.dev](https://daily.dev/posts/rag-is-blind-to-time-i-built-a-temporal-layer-to-fix-it-in-production-n1qi1u6py)