LlamaIndex is an open-source data orchestration framework for building production-ready LLM applications, specializing in retrieval-augmented generation (RAG) and agentic document workflows. It connects private or domain-specific data to large language models through sophisticated indexing, retrieval, and query mechanisms. Unlike general-purpose orchestration frameworks, LlamaIndex prioritizes data ingestion pipelines, advanced retrieval strategies, and context engineering — making it the go-to choice when your application's success hinges on how well you retrieve and structure information before passing it to an LLM. The framework treats documents as first-class citizens, offering deep control over chunking, embedding, metadata extraction, hierarchical relationships, multi-step retrieval patterns, agentic workflows, and MCP integration — essential for knowledge-intensive production applications.
What This Cheat Sheet Covers
This topic spans 29 focused tables and 195 indexed concepts. Below is a complete table-by-table outline of this topic, spanning foundational concepts through advanced details.
Table 1: Core Index Types
| Index | Example | Description |
|---|---|---|
index = VectorStoreIndex.from_documents(docs) | • Stores vector embeddings of document chunks • retrieves via similarity search (cosine, Euclidean) • most common index for semantic retrieval in RAG. | |
index = SummaryIndex.from_documents(docs) | • Stores nodes as a sequential chain with no complex structure • retrieves all nodes or filters by keywords • formerly called ListIndex. | |
index = DocumentSummaryIndex.from_documents(docs) | • Extracts a summary per document and stores it alongside nodes • retrieves by matching query to document summaries first, then fetches relevant nodes. | |
index = PropertyGraphIndex.from_documents(docs) | • Creates a knowledge graph with entities and relationships • supports Cypher queries, hybrid search, and graph-based retrieval for complex relational data. |