What is LlamaIndex?

LlamaIndex (formerly GPT Index) is a specialized data framework designed specifically for connecting LLMs with your external data sources. It excels at indexing, structuring, and querying data to build powerful Retrieval-Augmented Generation (RAG) applications.

At Predictive Tech Labs, we use LlamaIndex when data ingestion, indexing strategy, and query optimization are critical to application performance. It's the perfect choice for document-heavy applications requiring sophisticated retrieval mechanisms.

LlamaIndex RAG Pipeline Architecture

A
📁
Data Sources

PDFs, APIs, Databases, Web Pages, Documents

B
📄
Data Connectors

LlamaHub loaders for 100+ data sources

C
✂️
Chunking

Smart text splitting with overlap & metadata

D
🔢
Embedding

Convert chunks to vector representations

E
🗄️
Index Creation

Build optimized index structures

1
User Query

Natural language question input

2
🔍
Query Engine

Semantic search & retrieval

3
📋
Context Assembly

Rank & combine relevant chunks

4
🤖
LLM Generation

Generate answer with context

5
💬
Response

Formatted answer with citations

LlamaIndex Index Types

Choose the right index structure for your use case

📊 Vector Store Index

✨ Best For: Large document collections, semantic search
  • Stores embeddings in vector databases
  • Supports Pinecone, Weaviate, ChromaDB
  • Hybrid search capabilities
  • Scales to millions of documents
  • Real-time updates and inserts

📝 List Index

✨ Best For: Small datasets, comprehensive answers
  • Sequential document processing
  • Iterates through all documents
  • No embedding required
  • Good for summarization tasks
  • Simple but thorough

🌳 Tree Index

✨ Best For: Hierarchical data, summaries
  • Bottom-up tree construction
  • Hierarchical summarization
  • Efficient for large texts
  • Multi-level retrieval
  • Adaptive querying

🗝️ Keyword Table Index

✨ Best For: Keyword-based search, metadata filtering
  • Extracts keywords from each chunk
  • Fast keyword matching
  • Combines with semantic search
  • Metadata-aware retrieval
  • Structured data queries

📖 Document Summary Index

✨ Best For: Document-level summaries
  • Generates document summaries
  • Two-stage retrieval
  • Summary-based filtering
  • Reduces search space
  • Improved relevance

🔗 Knowledge Graph Index

✨ Best For: Relationship-based queries
  • Extracts entity relationships
  • Graph-based traversal
  • Complex query patterns
  • Multi-hop reasoning
  • Semantic connections

Why LlamaIndex Excels at RAG

🎯

RAG-First Design

Built specifically for retrieval-augmented generation from the ground up. Every feature optimized for connecting data to LLMs.

🔌

100+ Data Loaders

LlamaHub provides pre-built connectors for virtually every data source: PDFs, Notion, Slack, SQL databases, and more.

Query Optimization

Advanced query engines with routing, fusion, and multi-step retrieval strategies for maximum accuracy.

🎨

Flexible Indexing

Multiple index types let you choose the best structure for your data and query patterns.

📈

Observability

Built-in token usage tracking, retrieval metrics, and debugging tools for production monitoring.

🔄

Composability

Combine multiple indices, create hierarchies, and build complex RAG architectures with ease.

Advanced Query Engines

LlamaIndex provides sophisticated query strategies

🔍

Vector Store Query

Semantic similarity search using embeddings. Returns the most relevant chunks based on vector distance.

🌐

Sub-Question Query

Breaks complex questions into sub-queries, retrieves for each, then synthesizes a comprehensive answer.

🎯

Router Query Engine

Routes queries to the most appropriate index or retrieval strategy based on query type.

🔄

Transform Query

Applies transformations like query rewriting, HyDE (Hypothetical Document Embeddings), and decomposition.

📊

SQL Query Engine

Converts natural language to SQL queries for structured database interrogation.

🧩

Multi-Step Query

Sequential retrieval and reasoning for complex, multi-hop questions requiring multiple lookups.

Real-World Applications

📚 Enterprise Knowledge Bases

Index thousands of internal documents, wikis, and procedures. Employees get instant answers with source citations.

Vector Index PDF Loader Metadata Filters

⚖️ Legal Document Analysis

Search through contracts, case law, and regulations. Extract clauses, identify risks, and ensure compliance.

Document Summary Keyword Table Citation Tracking

🏥 Medical Research Assistant

Query research papers, clinical guidelines, and patient records. HIPAA-compliant with source verification.

Knowledge Graph Metadata Routing Entity Extraction

💼 Financial Analysis

Analyze earnings reports, 10-Ks, and market research. Compare companies and extract key metrics.

Tree Index Sub-Question Structured Data

Quick Start Example

Build a RAG application in minutes

from llama_index import VectorStoreIndex, SimpleDirectoryReader
from llama_index.vector_stores import PineconeVectorStore

# Load your documents
documents = SimpleDirectoryReader('data').load_data()

# Create vector store
vector_store = PineconeVectorStore(api_key="your-key")

# Build the index
index = VectorStoreIndex.from_documents(
    documents,
    vector_store=vector_store
)

# Query your data
query_engine = index.as_query_engine()
response = query_engine.query("What are the main findings?")
print(response)

Build Your RAG Application with LlamaIndex

Let's create a powerful document Q&A system tailored to your data