# Security and Multi-Tenancy — Vector Databases

Source: https://www.geekswithgeeks.com/en/vector-databases/s-secure

> Isolate tenants and protect data in transit, at rest and in queries.

## Enforce isolation where the data is

Embeddings are derived from your documents and can **leak information about them**, so vectors and payloads deserve the **same protection as the source data**. Use **TLS** in transit and **encryption at rest**; **authenticate** every client and give **least-privilege roles** (the ingestion service can write, the search service can only read); keep the database on a **private network**, never open to the internet; and keep **API keys in a secrets manager**. For **multi-tenancy**, enforce the tenant boundary where the data lives: **row-level security** or a mandatory tenant predicate in PostgreSQL, a **collection or namespace per tenant**, or an engine feature for tenant isolation; do not rely on application prompts or UI. **Test isolation** with automated checks that a tenant-A query never returns tenant-B rows. Log queries and administrative actions, and apply retention and **deletion** rules (deleting a document must delete its vectors and any caches).

## Protect it, keep it, pick it

Vectors are as sensitive as their sources; plan backups and migrations, then choose with evidence.

![Three tasks: secure, preserve, choose.](assets/figures/vector-databases/section-7-map.svg) — Figure 7.1 — Secure, preserve and choose.

## Row-level security in PostgreSQL (illustrative)

Every query on the table is automatically restricted to the tenant set for the session. Standard PostgreSQL feature; shown as a pattern, not run here.

```sql
ALTER TABLE docs ENABLE ROW LEVEL SECURITY;
CREATE POLICY tenant_isolation ON docs
  USING (tenant = current_setting('app.tenant'));

-- in each request, after authenticating the user:
--   SET LOCAL app.tenant = 'acme';
--   SELECT id, body FROM docs ORDER BY embedding <=> :q LIMIT 5;   -- can only see acme's rows
```

## Write a tenant-isolation test

Automatically check that a query as tenant A never returns a row of tenant B, and run it in CI.

**Quiz:** Where should tenant isolation be enforced?

- [ ] Only in the UI
- [ ] Only in the prompt
- [x] In the database (row-level security, collections or namespaces), tested automatically
- [ ] Nowhere

*Answer:* In the database (row-level security, collections or namespaces), tested automatically. Isolation must hold even if application code or prompts are wrong.