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What is the difference between a vector index and a vector database?

A vector index and a vector database serve different purposes in managing and querying vector data, though they are often used together in AI and machine learning applications.

Vector Index

A vector index is a data structure optimized for fast similarity search (e.g., nearest neighbor search) in high-dimensional vector spaces. It organizes vectors to enable efficient retrieval without scanning the entire dataset. Common types include:

  • Flat Indexes (e.g., Brute Force): Searches all vectors, accurate but slow for large datasets.
  • Approximate Nearest Neighbor (ANN) Indexes (e.g., HNSW, IVF, PQ): Trade slight accuracy for speed, ideal for large-scale vector search.

Example: An HNSW (Hierarchical Navigable Small World) index speeds up image retrieval by organizing embeddings for quick similarity matching.

Vector Database

A vector database is a specialized system that stores, manages, and queries vector data at scale. It integrates vector indexes, provides APIs for CRUD operations, and supports advanced features like metadata filtering, versioning, and scalability.

Example: A vector database can store product image embeddings, allowing e-commerce platforms to retrieve visually similar items using metadata filters (e.g., "red shoes under $50").

Key Differences

Feature Vector Index Vector Database
Purpose Optimizes similarity search Manages and queries vector data
Scope Focuses on search efficiency Handles storage, indexing, and APIs
Features Limited to search logic Supports metadata, scalability, etc.

Use Case in Cloud Services

For scalable vector search, Tencent Cloud’s VectorDB combines efficient indexing (e.g., HNSW) with database capabilities, enabling fast similarity search for AI applications like recommendation systems, image retrieval, and semantic search. It supports hybrid queries (vector + metadata) and auto-scaling for dynamic workloads.

Example: A video platform uses Tencent Cloud VectorDB to index video embeddings, allowing users to find similar content based on visual and textual features while filtering by tags or upload date.