antigravity-skills-reference/skills/dbos-golang/references/queue-deduplication.md

title, impact, impactDescription, tags

title	impact	impactDescription	tags
Deduplicate Queued Workflows	HIGH	Prevents duplicate workflow executions	queue, deduplication, idempotent, duplicate

Deduplicate Queued Workflows

Set a deduplication ID when enqueuing to prevent duplicate workflow executions. If a workflow with the same deduplication ID is already enqueued or executing, a DBOSError with code QueueDeduplicated is returned.

Incorrect (no deduplication):

// Multiple calls could enqueue duplicates
func handleClick(ctx dbos.DBOSContext, userID, task string) error {
	_, err := dbos.RunWorkflow(ctx, processTask, task,
		dbos.WithQueue(queue.Name),
	)
	return err
}

Correct (with deduplication):

func handleClick(ctx dbos.DBOSContext, userID, task string) error {
	_, err := dbos.RunWorkflow(ctx, processTask, task,
		dbos.WithQueue(queue.Name),
		dbos.WithDeduplicationID(userID),
	)
	if err != nil {
		// Check if it was deduplicated
		var dbosErr *dbos.DBOSError
		if errors.As(err, &dbosErr) && dbosErr.Code == dbos.QueueDeduplicated {
			fmt.Println("Task already in progress for user:", userID)
			return nil
		}
		return err
	}
	return nil
}

Deduplication is per-queue. The deduplication ID is active while the workflow has status ENQUEUED or PENDING. Once the workflow completes, a new workflow with the same deduplication ID can be enqueued.

This is useful for:

• Ensuring one active task per user
• Preventing duplicate form submissions
• Idempotent event processing

Reference: Deduplication