Implementing Microsoft Graph Delta Queries for User Synchronization

The Problem: Polling Latency and API Throttling

Synchronizing local databases with Microsoft 365 user data often leads to a choice between two inefficient patterns: polling the entire /users endpoint frequently, which triggers 429 Too Many Requests throttling, or polling infrequently, which leaves local data stale. To maintain a near real-time mirror of user objects without exhausting API quotas, you must implement Delta Queries.

The takeaway is that Delta Queries shift the burden of change-tracking from the client to the Microsoft Graph backend. Instead of requesting all users and comparing them locally, the client requests only the changes (deltas) that occurred since the last synchronization point using an opaque state token.

How Delta Queries Work

A delta query is a specialized GET request that returns a set of changes. The process follows a specific state machine: the Initial Sync, the Delta Loop, and the Pagination phase.

1. The Initial Sync

The first request is made to the /delta child endpoint of the resource collection. This returns the current state of all users. Because this dataset is often large, the response will likely include an @odata.nextLink for pagination.

2. The Delta Link

Once the initial dataset is fully exhausted (i.e., no more @odata.nextLink is present), the final response contains an @odata.deltaLink. This URL contains a state token that represents the exact point in time the synchronization reached.

3. The Incremental Sync

To check for updates, the client calls the @odata.deltaLink. Graph returns only users who were created, updated, or deleted since the token was generated. If no changes occurred, the response is empty but still provides a new @odata.deltaLink for the next check.

Worked Implementation Example

To implement this, you need an application registered in Azure AD (Microsoft Entra ID) with User.Read.All application permissions. All requests must be run against the https://graph.microsoft.com/v1.0 base URL.

Step 1: Initial Request

Run this request to begin the synchronization process:

GET /users/delta?$select=displayName,mail,jobTitle

Step 2: Handling the Response

The response body will look like this. Note the @removed property, which indicates a user was deleted in M365:

{
  "value": [
    {
      "id": "user-123",
      "displayName": "Jane Doe",
      "mail": "[contact removed]"
    },
    {
      "id": "user-456",
      "@removed": { "data": {} }
    }
  ],
  "@odata.nextLink": "https://graph.microsoft.com/v1.0/users/delta?token=abc..."
}

Step 3: The Sync Loop Logic

Your synchronization logic should follow this decision tree:

• If @odata.nextLink exists: Follow it immediately to get the next page of the current state.
• If @odata.deltaLink exists: Store this URL in your database. Use it for the next scheduled sync (e.g., every 15 minutes).
• If @removed is present: Delete the corresponding record from your local cache using the provided id.

Limitations and Common Pitfalls

Delta Link Expiration

Delta links are not permanent. If a client fails to call the @odata.deltaLink for an extended period (typically several days), the token expires. When this happens, the API returns a 410 Gone error. Your application must be programmed to catch this specific error, discard the expired token, and restart the Initial Sync from scratch.

Pagination vs. Delta

A common mistake is confusing the nextLink with the deltaLink. The nextLink is for pagination (getting the rest of the current data); the deltaLink is for synchronization (getting changes in the future). If you store a nextLink as your sync token, you will miss all changes that occurred between the first page and the last page of the initial sync.

Resource Support

Not all Graph endpoints support delta queries. While /users, /groups, and /drive/items do, many custom or niche endpoints do not. Always verify the endpoint documentation before designing your sync architecture.

Verification Checklist

To verify your implementation is working correctly, perform these three tests in a development tenant:

1. Update Test: Change a user's jobTitle in the M365 Admin Center. Call your stored deltaLink and verify that only that specific user is returned in the value array.
2. Deletion Test: Delete a test user. Call the deltaLink and verify the user appears with the @removed attribute.
3. Empty State Test: Call the deltaLink when no changes have occurred. Verify that the value array is empty but a new @odata.deltaLink is provided.