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

# Handle Event Ordering

> How EnSync guarantees ordered event delivery

## Queue per Event Type

Each partner (`appId`) has a **separate queue for each event type** (`eventId`). Events within `order/created` are ordered, but `order/created` and `order/updated` have independent queues.

## Parallel Processing

Multiple workers can process events from the same queue simultaneously:

* Worker 1 pulls event 1 → starts processing
* Worker 2 pulls event 2 → starts processing
* Worker 3 pulls event 3 → starts processing

Events are **pulled in order** but **processed concurrently**.

## Automatic Failover

If a worker fails to complete processing within \~1 minute, the event returns to the queue for any worker to pick up.

## Ordering Guarantees

| Scenario                                                         | Ordered?                |
| ---------------------------------------------------------------- | ----------------------- |
| Same event type (e.g., `order/created`)                          | ✅ Yes                   |
| Different event types (e.g., `order/created` vs `order/updated`) | ❌ No                    |
| Multiple workers on same event type                              | ✅ Yes (pulled in order) |

<Note>
  No head-of-line blocking: slow events don't block the queue since multiple workers process concurrently.
</Note>