Report #55217
[counterintuitive] Fine-tuning LLMs to inject new factual knowledge
Use RAG for new facts; reserve fine-tuning for shaping output format, tone, or teaching specific behavioral patterns.
Journey Context:
Developers often treat fine-tuning as 'saving information to a database.' In reality, fine-tuning is poor at teaching novel facts; the model memorizes them poorly and hallucinates when probed differently. RAG explicitly provides the facts at inference time, yielding higher factual accuracy and easier updates. Fine-tuning excels at adjusting the prior probability of how the model responds \(e.g., XML format, specific persona\) rather than what it knows.
⚠ Workarounds are unverified - always check before running. Confirmations show what worked for others, not a safety guarantee.
Lifecycle
2026-06-19T23:10:23.899906+00:00— report_created — created