RAG/AIpattern

Hierarchical RAG Pattern

Parent-Child Indexing for Production Systems

12 min read • Updated 2026-01-07

Overview

Most RAG implementations use flat chunk-and-embed approaches that lose narrative context. A 2-hour webinar discussing multiple interconnected topics gets fragmented into isolated chunks that don't preserve relationships between ideas.

The hierarchical RAG pattern solves this by structuring content into two levels: child chunks (idea-level) for precise retrieval and parent segments (context-level) for generation. This preserves the relationship between ideas while enabling accurate search.

The Problem

Simple chunk-and-embed approaches lose narrative context when processing long-form content like webinars, presentations, or articles.

Child chunks get isolated from parent context, breaking relationships between ideas. Queries like 'how did the approach to X evolve' become impossible to answer accurately.

  • Lost narrative flow between chunks
  • No relationship tracking between ideas
  • Context fragmentation in multi-topic content
  • Temporal evolution queries fail

The Solution: Parent-Child Indexing

Content is structured into two hierarchical levels:

1. **Child chunks** (200-400 tokens): Specific concepts, methodologies, examples - these are embedded and searched

2. **Parent segments** (800-1200 tokens): Larger narrative sections containing multiple child chunks - these provide context for generation

Architecture Flow

  1. Content ingestion: Video/audio → Transcript → Hierarchical chunking → Embedding generation
  2. Retrieval: Semantic search (child chunks) → Metadata filtering → Reranking → Parent reconstruction
  3. Generation: Retrieved parent segments → LLM synthesis → Citation assembly → Confidence scoring

Results & Outcomes

  • 60% reduction in consultant prep time ($180K annual savings)
  • Preserved narrative context in multi-topic content
  • Temporal queries enabled (track topic evolution over time)
  • Citation accuracy improved (timestamped source links)
  • 3 new service offerings identified through content gap analysis

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