Agentic AI Reference Architecture

Knowledge & Data · Data store

Lexical Index Store

Data storeKnowledge & DataKnowledge & Dataarc:FullTextIndexStore

An index over the full text of the corpus supporting sparse term-based scoring (e.g., BM25) for exact keyword and phrase matching.

Responsibility. Stores tokenized corpus text for sparse lexical scoring.

Also known as: BM25 index, Sparse index, Keyword index, Full-text search engine, Inverted text index, Full-text index, Full-Text Search Index, Lexical Index Store

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Direct neighbourhood (hover for relationship types)

Relationships

is read by dependency

is written by dependency

Classification

Patterns
BM25Inverted indexBM25 keyword matching
Quality attributes
Reliability (ISO/IEC 25010 | NIST AI RMF: valid and reliable)Functional suitability: correctness and validity (ISO/IEC 25010 | NIST AI RMF: valid)

Sources

  1. Ch6.1: T. Nguyen, "Embeddings and RAG Fundamentals," in Mastering Agentic AI Systems: Guide for the NVIDIA NCP-AAI Exam, 1st ed. 2026, ch. 6.1. ISBN: 9798244538229.
  2. Ch6.2A: T. Nguyen, "Vector Database Selection," in Mastering Agentic AI Systems: Guide for the NVIDIA NCP-AAI Exam, 1st ed. 2026, ch. 6.2A. ISBN: 9798244538229.
  3. Ch6.3A: T. Nguyen, "ETL Pipeline Fundamentals," in Mastering Agentic AI Systems: Guide for the NVIDIA NCP-AAI Exam, 1st ed. 2026, ch. 6.3A. ISBN: 9798244538229.
  4. Ch6.5: T. Nguyen, "Production RAG Systems," in Mastering Agentic AI Systems: Guide for the NVIDIA NCP-AAI Exam, 1st ed. 2026, ch. 6.5. ISBN: 9798244538229.