What metadata should you attach to each chunk for RAG?

Attach metadata that supports filtering, attribution, and display: source document identifier or URL, page or section number, document title, author or owner, creation and modification dates, and domain-specific tags like product, language, or access-control group. Metadata lets you filter retrieval to specific sources, boost recent documents, restrict results by user permissions, and show users where each answer came from. Vector databases index metadata separately for fast filtered search without scanning every vector.