What Is a Vector Database (and Do You Need One)?
Vector databases went from obscure to mandatory-sounding in two years. You may need one. You may also already have one hiding inside the database you run today.
- Published
What it stores
A vector database stores embeddings — lists of numbers that represent the meaning of a piece of text or an image — and finds the stored items closest to a query vector. "Closest" means "most similar in meaning", which is what makes semantic search work.
Your options
| Option | Good for | Trade-off |
|---|---|---|
| Vector extension on Postgres | Up to millions of vectors, apps already on Postgres | One less system; tuning needed at scale |
| Managed vector database | Large scale, many tenants, high query volume | Another vendor and bill |
| Search engine with vector support | Hybrid keyword + semantic search | Heavier to operate |
| In-memory index | Prototypes, small static sets | Not durable |
Do you need a dedicated one?
For most business assistants — tens of thousands to a few million chunks — a vector extension on the Postgres you already run is enough and keeps permissions, backups and joins in one place. A dedicated vector database earns its place at very large scale, very high query rates, or when you need features like multi-tenant isolation out of the box.
What matters more than the database
- Chunking quality — bad chunks cannot be rescued by a fast index.
- Hybrid search — combining keyword and vector search fixes exact-term misses.
- Reranking — a second pass that reorders the top results improves answer quality.
- Permission filtering — every query must respect who can see what.
Frequently asked questions
Is a vector database a replacement for my main database?
No. It is a search index. Your source of truth stays where it is.
How much does one cost?
Postgres extensions add little cost. Managed services charge by storage and queries; at business-assistant scale it is usually modest.
Can I switch later?
Yes, if embeddings and chunking live in your own pipeline. We keep them portable by design.
