Implement tenant isolation using vector store namespaces (physical isolation) or metadata filtering (logical isolation). Namespaces provide physical separation per tenant with no cross-tenant leaks and lower filtering overhead, while metadata filters offer flexibility and shared infrastructure at the cost of query-time filtering overhead.
Multi-tenant RAG requires strict data isolation to prevent cross-tenant leaks. Most vector stores support two isolation patterns: namespace isolation (physical separation per tenant) and metadata filtering (logical separation with query-time filters). Namespaces (e.g., Pinecone namespaces, Qdrant shard keys) ensure complete separation with no filtering overhead[reference:33], while metadata filters (e.g., adding tenant_id field) allow sharing a single collection with per-query filtering, ideal for many small tenants[reference:34].
Namespace isolation: Physical separation, best for large tenants (millions of vectors), no filtering overhead, requires per-tenant collections/indices[reference:35]
Metadata filtering: Logical separation with shared index, good for many small tenants, query-time filtering overhead, easier management, requires proper indexing on filter fields[reference:36]
Row-level security (RLS): Database-level enforcement (PostgreSQL), automatic tenant isolation, transparent to application code[reference:37]
Tenant propagation: Tenant context extracted from auth token and passed through all services and middleware[reference:38]
Per-tenant rate limits: Tie quotas to tenant ID to prevent abusive usage[reference:39]