Hybrid RAG, reranking, and parent-child retrieval
Words made simple
A few useful meanings before you read the explanation.
- RAG
- Find relevant information first, then give it to a model to help answer the question. The answer is only as reliable as the information and checks used.
- Retrieval
- Finding and fetching information that is useful for the current question.
- Reranking
- Checking an initial set of search results again and putting the most useful ones nearer the top.
More words from this lesson
- Token
- A small piece of text processed by a model. It may be a whole word, part of a word, or punctuation.
- Grounding
- Connecting an answer to supplied evidence, such as a policy document or a verified database result.
- Authorization
- Checking what that identity is allowed to read or do. Being logged in does not grant access to every record.
- Chunking
- Dividing a long document into smaller pieces so relevant parts can be found and sent to the model.
Overview
- Hybrid RAG uses lexical and semantic retrieval together.
- Reranking carefully orders the retrieved candidates.
- Parent-child retrieval searches smaller child chunks but supplies a larger parent section when the child is selected.
Why this matters
Search benefits from precise units, while answering often requires surrounding qualifications.
An everyday example
Find the right paragraph through an index, then read its whole section before explaining it.
A technical example
Retrieve a child containing “theft” and expand to its parent section including exclusions and required police-report conditions.
How it works
- Index parent/child relationships
- Hybrid retrieve children
- Rerank
- Load authorized parent sections
- Deduplicate
- Budget context.
Architecture and flow
Hybrid child retrieval → rerank → parent expansion → grounded answer.
The insurance assistant example
A short hit about vehicle damage should bring in the adjacent exception that changes coverage.
When to use it
Structured manuals and policies with conditions distributed around matching phrases.
When to avoid it
Avoid parent expansion when parents are huge, irrelevant, or have different access permissions.
Interview answer
“I search precise chunks and expand only to the supporting section when the answer needs surrounding context.”
Benefits, trade-offs, and production considerations
- Parent expansion raises token usage.
- Preserve child source coordinates, apply ACLs at every loaded level, and evaluate whether expansion improves correctness rather than only making answers longer.
Can you explain it without the notes?
Hybrid RAG, reranking, and parent-child retrieval
Use your own words. Explain an example and one limitation before checking the explanation.
Check your explanation
Hybrid RAG uses lexical and semantic retrieval together. Reranking carefully orders the retrieved candidates. Parent-child retrieval searches smaller child chunks but supplies a larger parent section when the child is selected.
Turn this concept into a clear answer.
Practice this conceptAdapted from 13_AI.MD · “Hybrid RAG, reranking, and parent-child retrieval”. Examples are study fragments; framework behavior can depend on your version.