IsTombstone
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Category: Client Connectivity & SDK
Overview
Tombstone in Azure Cosmos DB: When an item is deleted from a container, Azure Cosmos DB marks the item as a "tombstone" to ensure that the deletion is propagated correctly across all replicas in a distributed system. This ensures that the deleted item does not reappear after a replica catches up or after a period of network partition. For DP-420, if you see tombstones, think: Change Feed Delete notifications All Versions and Deletes mode CDC (similar to SQL Server Change Data Capture)
| Mode | Creates | Updates | Deletes |
| ----------------------------- | ------- | ------- | -------------- |
| Latest Version Mode | ✅ | ✅ | ❌ |
| All Versions and Deletes Mode | ✅ | ✅ | ✅ (tombstones) |
More Info & Links
DP-420 Style Practice Questions
Q1. What does a 429 error from Azure Cosmos DB typically indicate?
- A. The request was throttled because provisioned throughput (RU/s) was exceeded
- B. The requested item does not exist
- C. An authentication failure occurred
- D. A conflict occurred during multi-region writes
Q2. Which of these could help reduce the frequency of 429 errors?
- A. Improving partition key distribution to avoid hot partitions, or increasing provisioned RU/s
- B. Disabling the SDK's automatic retry policy
- C. Switching to gateway mode exclusively
- D. Reducing the number of properties indexed
Answer Key
Answers are listed at the very end so you can attempt the questions first.
- Q1 (429 Throttling Error): A. The request was throttled because provisioned throughput (RU/s) was exceeded — A 429 status code means the request rate exceeded the provisioned RU/s, triggering throttling.
- Q2 (429 Throttling Error): A. Improving partition key distribution to avoid hot partitions, or increasing provisioned RU/s — Better partition key distribution and/or higher provisioned throughput both help reduce 429 throttling errors.
DP-420: Designing and Implementing Cloud-Native Applications Using Microsoft Azure Cosmos DB — term detail page
