Chroma’s data model is designed to balance simplicity, flexibility, and scalability. It introduces a few core abstractions—Tenants, Databases, and Collections—that allow you to organize, retrieve, and manage data efficiently across environments and use cases.
A collection is the fundamental unit of storage and querying in Chroma. Each collection contains a set of items, where each item consists of:
An ID uniquely identifying the item
An embedding vector
Optional metadata (key-value pairs)
A document that belongs to the provided embedding
Collections are independently indexed and are optimized for fast retrieval using vector similarity, full-text search, and metadata filtering. In distributed deployments, collections can be sharded or migrated across nodes as needed; the system transparently manages paging them in and out of memory based on access patterns.
Collections are grouped into databases, which serve as a logical namespace. This is useful for organizing collections by purpose—for example, separating environments like “staging” and “production”, or grouping applications under a common schema.Each database contains multiple collections, and each collection name must be unique within a database.
At the top level of the model is the tenant, which represents a single user, team, or account. Tenants provide complete isolation. No data or metadata, is shared across tenants. All access control, quota enforcement, and billing are scoped to the tenant level.
