Getting Started with Vector Databases Using Amazon Aurora PostgreSQL + pgvector

Hello! I'm Satoshi Kaneyasu, DevOps engineer at Serverworks. In this article, I'll introduce the basic concepts and terminology of vector databases for those who are just starting to learn about them. Target Audience This article is aimed at beginners to vector databases. You may have heard that vector databases are related to LLMs and RAG, but aren't quite sure what they actually are. Think of this as written with that kind of reader in mind. What Is a Vector Database? A vector database is a database that stores data as vectors (arrays of numbers) and searches for data using "distance" or "similarity" between vectors. Traditional relational databases search for data using "exact match" or "partial match" (LIKE queries), but vector databases can search for things that are semantically similar . For example, searching for "weather in Tokyo" might return results like "temperature in Tokyo" or "weather conditions in Kanto" — data that differs as a string but is semantically related. Visualizing Vector Space In a vector database, all data is represented as points in a multidimensional space. When searching, the query is also converted into a vector, and data that is "close in distance" within that space is retrieved. This diagram represents it in two dimensions, but in a real vector database, proximity and distance are defined across many dimensions. Use Cases for Vector Databases Vector databases are used across a wide range of applications: Use Case Description RAG (Retrieval-Augmented Generation) Knowledge base search to provide external knowledge to LLMs. Allows internal documents and up-to-date information to be reflected in LLM responses Semantic Search Searching internal documents or FAQs by meaning rather than keywords. Handles spelling variations and synonyms Recommendation Recommending products and content whose vectors are close to a user's preference vector. Used as an alternative or complement to collaborative filtering Image Search Searching for similar im