Databricks Generative AI Engineer Associate: Building LLM Chains

An LLM chain makes a generative AI application easier to reason about by turning one large prompt-driven task into a sequence of explicit transformations. A chain might validate input, retrieve supporting context, build a prompt, call a model, parse a structured response, apply business rules, and return a final result.

The current Generative AI Engineer exam still expects candidates to understand LLM chains, including selecting chain components, coding simple chains, using pre- and post-processing, retrieval, registration, and deployment. The practical goal inside Databricks GenAI is to make each stage testable so quality improvements do not depend on editing one opaque prompt and hoping the whole application gets better.

Define the input and output contract first

A chain should have a clear contract at its boundary. Inputs might include a user question, account identifier, document, or structured fields.

Use a chain when the sequence is known

Chains are strongest when the required steps are deterministic. If every request should retrieve context, construct a prompt, call a model, and validate a response, there is little value in asking an agent to rediscover that sequence every time.

Keep preprocessing narrow and explainable

Preprocessing can normalize input, extract key fields, remove irrelevant content, or classify the request before the main model call. The danger is letting preprocessing become an invisible second model that changes meaning.

Retrieval should be one observable component

A RAG chain normally retrieves evidence before generation. The quality of that stage depends on document preparation, chunking, embeddings, metadata, query construction, filtering, and reranking.

Prompt construction should separate instructions from data

A good chain knows which text is policy, which text is user input, and which text is retrieved evidence. Keeping those roles distinct reduces accidental instruction conflicts and makes prompt-injection controls easier to reason about.