7e5abd504f
Add three DBOS SDK skills with reference documentation for building reliable, fault-tolerant applications with durable workflows. Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>
53 lines
1.6 KiB
Markdown
53 lines
1.6 KiB
Markdown
---
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title: Deduplicate Queued Workflows
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impact: HIGH
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impactDescription: Prevents duplicate workflow executions
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tags: queue, deduplication, idempotent, duplicate
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---
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## Deduplicate Queued Workflows
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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.
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**Incorrect (no deduplication):**
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```go
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// Multiple calls could enqueue duplicates
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func handleClick(ctx dbos.DBOSContext, userID, task string) error {
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_, err := dbos.RunWorkflow(ctx, processTask, task,
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dbos.WithQueue(queue.Name),
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)
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return err
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}
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```
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**Correct (with deduplication):**
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```go
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func handleClick(ctx dbos.DBOSContext, userID, task string) error {
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_, err := dbos.RunWorkflow(ctx, processTask, task,
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dbos.WithQueue(queue.Name),
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dbos.WithDeduplicationID(userID),
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)
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if err != nil {
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// Check if it was deduplicated
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var dbosErr *dbos.DBOSError
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if errors.As(err, &dbosErr) && dbosErr.Code == dbos.QueueDeduplicated {
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fmt.Println("Task already in progress for user:", userID)
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return nil
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}
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return err
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}
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return nil
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}
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```
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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.
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This is useful for:
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- Ensuring one active task per user
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- Preventing duplicate form submissions
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- Idempotent event processing
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Reference: [Deduplication](https://docs.dbos.dev/golang/tutorials/queue-tutorial#deduplication)
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