Reltio ID overview
Learn how to generate and maintain a unique and durable identifier to track data across all your applications inside and outside the Reltio platform.
Take a sneak peek at Reltio ID - your unique, durable identifier.
Are you a Data Steward or a
Business User who is in charge of handling customer data across multiple disconnected analytical environments and distributed systems across your organization?
Does your management team often have discussions on implementing a costly and time-consuming in-house solution to build an identifier that can be used to identify an entity uniquely across all these different systems?
If this sounds like you, perhaps you could use a universal identifier generated in Reltio for every unique entity. This identifier can be used to connect and tie the entities' data spread across your distributed systems. It enables you to match and complete data across your applications, which ultimately leads to better data quality, accurate analytics reporting, and good business decisions.
What is Reltio ID?
Reltio ID is a system-generated, UUID v6-based identifier that ensures every entity in your tenant has a durable, globally unique reference. It is automatically assigned to new entities created in your tenant
When Reltio ID generation is enabled, a new Reltio ID is assigned each time an entity is created — unless the entity merges on the fly with an existing entity that already has a Reltio ID.
Reltio ID generation for existing and cloned tenants
Reltio ID generation doesn’t apply retroactively to existing records when the feature is enabled. To assign Reltio IDs to existing entities, run the Generate Reltio ID task.
- For new tenants or entity types: Reltio IDs are created on-the-fly as new entities are added.
- For existing tenants: Run the task manually to generate IDs for existing records.
- For cloned tenants or profiles: Reltio IDs from the source tenant are cloned by default. Run the task with
regenerate=trueto assign new, unique Reltio IDs.
Benefits of using Reltio ID
- Durable: Reltio ID is durable and unique for an entity within a tenant. It remains stable across data reloads and can be used for consistent identification. Note: The Entity ID can’t be used as a durable identifier since it changes every time data is loaded into a new environment.
- High latency search: The search by Reltio ID API supports hyper performance. Get your search results quick as a wink.
- Reuse: You can reuse the earlier generated ID or generate a new ID when you reload data into a tenant.
Custom UID
In addition to using a system-generated Reltio ID, you can configure any attribute in your entity as a Custom UID. This attribute is treated as a durable, unique identifier within your tenant.
Custom UIDs provide similar benefits to Reltio IDs. For example, you can use a medical license number or Social Security Number (SSN) as a Custom UID.
Crosswalk behavior for Reltio ID and Custom UID
When a Reltio ID is generated—or a Custom UID is defined—Reltio automatically creates a crosswalk with:
- Source system:
ReltioID - Value: Either the generated Reltio ID or the provided Custom UID value
Reltio ID vs. Custom UID — Deep Dive Comparison
This table compares how Reltio ID and Custom UID work, including how they're configured, how they behave at runtime, and which use cases they best support.
| Feature | Reltio ID | Custom UID |
|---|---|---|
| Type of ID | System-generated UUID (v6) | User-defined, based on a specific attribute |
| Value source | Automatically created by Reltio at entity creation | Provided manually by user or loaded from source system |
| How to enable | Enable Reltio ID generation at the entity type level; add an attribute with type ReltioId | Mark an existing attribute with customReltioId: true in tenant configuration |
| Entity creation behavior | ID is generated during entity creation via UI, API, or Data Loader | Value must be present in the input; Reltio does not auto-generate |
| Works for relationships/interactions? | ❌ No | ❌ No |
| Uniqueness enforcement | ✅ Guaranteed by the system | ❌ Must be enforced by the user |
| Crosswalk created | ✅ Yes — a crosswalk with source system ReltioID and value = Reltio ID | ✅ Yes — same as Reltio ID; value = the custom UID |
| Survivorship support | ✅ Treated like a standard attribute, supports survivorship rules | ✅ Same survivorship behavior applies |
| Merge behavior | Multiple Reltio IDs from merged profiles are retained unless regenerated | Multiple Custom UID values can exist; OV determined by survivorship |
| Can be regenerated? | ✅ Yes — use GenerateReltioIdTask with regenerate=true | ❌ No — value must be replaced manually in data or through update |
| Used in search API | ✅ Yes — via /entities/_byReltioId/{value} endpoint | ✅ Yes — same endpoint, using the custom UID as crosswalk value |
| Data type requirement | Must be declared as type: ReltioId | Can be any supported type (e.g., String, Number, URL) |
| Operational Value (OV) eligible? | ✅ Yes | ✅ Yes |
| Multiple values allowed? | ✅ Multiple crosswalks with Reltio IDs can be stored and versioned | ✅ Multiple values can be stored; must use survivorship to manage active one |
| Persistence across loads | ✅ Persistent and durable across data loads, clones, and environments | ✅ Persistent if maintained in source data and uniqueness is preserved |
| Default system fallback | ✅ Yes — recommended when no external durable ID is available | ❌ No — only use when you already have a consistent, authoritative ID in your business systems |
How Reltio ID behaves in merges and survivorship
The Reltio Id and Custom UID attributes are treated like any other attribute:
- If several profiles are merged — each with its own Reltio ID — the resulting profile will contain multiple ReltioID crosswalks, increasing the total number of crosswalks.
- Each original (merged) profile contributes its own value.
- Reltio Id values are preserved unless regenerated by task.
You can define survivorship rules on the ReltioId and Custom UID attribute to control which value becomes the Operational Value (OV) shown in the UI and APIs.