Retrieval-Augmented Generation (RAG)
Combine your own data with an LLM by retrieving relevant documents and injecting them into the prompt, producing grounded, up-to-date answers.
Retrieval-Augmented Generation (RAG) is a free AI Powered SaaS: Stripe + Auth + Billing + Deploy lesson on CoddyKit — lesson 4 of 4. You can read the complete lesson below for free — then practise it hands-on in the browser with a built-in code editor and a 24/7 AI tutor. It is part of the AI Powered SaaS: Stripe + Auth + Billing + Deploy learning path, one of 4 lessons in the course, and your progress syncs across the web and the CoddyKit app.
What is RAG?
Retrieval-Augmented Generation gives an LLM access to external knowledge at query time. Instead of relying only on training data, you fetch relevant text and add it to the prompt.
- Answers stay current without retraining
- Reduces hallucinations
- Lets the model cite your private documents
The RAG Pipeline
A typical pipeline has two phases:
- Indexing: split documents into chunks, embed them, store vectors
- Retrieval + generation: embed the query, find similar chunks, feed them to the LLM
Chunking Documents
Split long documents into smaller chunks (often 200-500 tokens) with slight overlap. Good chunking keeps related ideas together so retrieval returns coherent context.
Creating Embeddings
An embedding model turns text into a numeric vector. Similar meanings produce nearby vectors. You embed every chunk during indexing.
const emb = await client.embeddings.create({
model: "text-embedding-3-small",
input: chunkText,
});
const vector = emb.data[0].embedding;Storing Vectors
Vectors live in a vector database such as pgvector, Pinecone, or Qdrant. Each record stores the vector plus metadata (source, title, chunk id) for later filtering and citation.
Retrieving Relevant Chunks
At query time you embed the user question and run a similarity search (cosine distance) to get the top-k closest chunks.
SELECT content FROM docs
ORDER BY embedding <=> $1
LIMIT 5;Building the Augmented Prompt
Insert the retrieved chunks into the prompt as context, then ask the model to answer using only that context.
const prompt = "Context:\n" + chunks.join("\n---\n") +
"\n\nQuestion: " + userQuestion +
"\nAnswer using only the context above.";Citing Sources
Because each chunk carries metadata, you can show citations next to the answer. This builds trust and lets users verify claims against the original document.
Handling No Good Match
If similarity scores are all low, the knowledge base probably lacks the answer. Detect this with a threshold and have the model reply that it does not know, rather than guessing.
Keeping the Index Fresh
When source documents change, re-embed and upsert the affected chunks. Track a content hash per chunk so you only re-index what actually changed, saving embedding cost.
Evaluating RAG Quality
Measure two things: retrieval quality (did we fetch the right chunks?) and answer quality (is the response grounded?). Use a test set of question and answer pairs and check whether the cited chunks contain the supporting facts.
Quick Check
Check your understanding of RAG.
Recap
You learned the full RAG flow:
- Chunk and embed documents into a vector store
- Embed the query and retrieve top-k similar chunks
- Augment the prompt and answer with citations
- Handle low-confidence matches and keep the index fresh
RAG grounds your AI features in your own data without retraining.
Frequently asked questions
Is the “Retrieval-Augmented Generation (RAG)” lesson free?
Yes — the full text of “Retrieval-Augmented Generation (RAG)” is free to read here on the web, and the AI Powered SaaS: Stripe + Auth + Billing + Deploy course includes 4 lessons in total. To practise it interactively (a built-in code editor and a 24/7 AI tutor) and unlock the rest of the AI Powered SaaS: Stripe + Auth + Billing + Deploy course, upgrade to CoddyKit PRO.
What will I learn in “Retrieval-Augmented Generation (RAG)”?
Combine your own data with an LLM by retrieving relevant documents and injecting them into the prompt, producing grounded, up-to-date answers. You practise AI Powered SaaS: Stripe + Auth + Billing + Deploy with hands-on code you run directly in the browser, and a 24/7 AI tutor answers your questions as you work through the lesson.
Do I need any experience to start AI Powered SaaS: Stripe + Auth + Billing + Deploy?
No prior experience is required. AI Powered SaaS: Stripe + Auth + Billing + Deploy on CoddyKit is structured for beginners through advanced learners; this is — lesson 4 of 4, so you can start here or from the beginning and move at your own pace.
How long does the “Retrieval-Augmented Generation (RAG)” lesson take?
Most CoddyKit lessons take about 5–10 minutes. Each one is bite-sized and interactive, so you make steady progress and pick up exactly where you left off across the web and the app.
Can I write and run code in this AI Powered SaaS: Stripe + Auth + Billing + Deploy lesson?
Yes. Every AI Powered SaaS: Stripe + Auth + Billing + Deploy lesson includes a built-in code editor, so you write and run real code right in your browser and get instant AI feedback — no local setup required.
All lessons in this course
- Fine-Tuning LLMs
- Real-time AI Processing
- Monitoring AI Performance
- Retrieval-Augmented Generation (RAG)