429 Throttling Error
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Category: Client Connectivity & SDK
Summary: Error indicating a request was rate-limited due to exceeding provisioned RU/s.
Overview
A 429 (Too Many Requests) error indicates that a request has been rate-limited because the container or database has exceeded its provisioned throughput (RU/s) for that period. Azure Cosmos DB SDKs typically handle 429s with automatic retry logic (honoring the x-ms-retry-after-ms header), but applications should also be designed to handle transient throttling gracefully, and may need to increase provisioned RU/s or improve partition key distribution to reduce 429s.
412 Precondition Failed: The request failed because a condition specified in a header (such as If-Match or If-None-Match) was not met.
413 Request Entity Too Large: The request body is larger than the allowed limit.
408 Request Timeout: The request timed out.
500 Internal Server Error: An unexpected error occurred on the server.
503 - Service Unavailable: The server is temporarily unable to handle the request.
423 - the resource is locked
The Conflict, Forbidden, and RequestEntityTooLarge HTTP responses correspond, respectively, to errors 409, 403, and 413.
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
