> ## Documentation Index
> Fetch the complete documentation index at: https://confidence.spotify.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Entities Reference

> Technical reference for entities in Confidence Metrics.

This section provides technical specifications and reference information for entities.

> [!TIP]
>
> For conceptual explanations of entities, see [Entities](https://confidence.spotify.com/docs/reference/api/metrics/concepts.md#entity) in the Metrics Concepts page.

## Primary Key Types

Available primary key types for entities:

| Type | Description | Use Case |
| :- | :- | :- |
| `COLUMN_TYPE_STRING` | String identifiers | UUIDs, usernames, session IDs |
| `COLUMN_TYPE_INTEGER` | Integer identifiers | Autoincrementing user IDs, numeric keys |
| `COLUMN_TYPE_BOOLEAN` | Boolean values | Binary entity identifiers (rarely used) |
| `COLUMN_TYPE_DOUBLE` | Floating point numbers | Numeric identifiers with decimals (rarely used) |

## Entity Constraints

* **Unique names**: Entity display names must be unique within a project
* **Immutable key type**: You cannot change the primary key type after creation
* **Referenced entities**: You cannot delete entities used in fact tables, dimension tables, or metrics
* **Case sensitivity**: Entity names are case-sensitive

## Entity Resource Name Format

Reference entities using the resource name format:

```text theme={null}
entities/{entity_id}
```

Example: `entities/user`, `entities/session`