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You are designing an Azure Cosmos DB Core (SQL) API solution to store data from IoT devices. Writes from the devices will be occur every second.
The following is a sample of the data.
You need to select a partition key that meets the following requirements for writes:
Minimizes the partition skew
Avoids capacity limits Avoids hot partitions
What should you do?
A. Use timestamp as the partition key.
B. Create a new synthetic key that contains deviceId and sensor1Value.
C. Create a new synthetic key that contains deviceId and deviceManufacturer.
D. Create a new synthetic key that contains deviceId and a random number.
ANSWER: D
Explanation:
Use a partition key with a random suffix. Distribute the workload more evenly is to append a random number at the end of the partition key value. When you distribute items in this way, you can perform parallel write operations across partitions.
Incorrect Answers:
A: You will also not like to partition the data on “DateTime”, because this will create a hot partition. Imagine you have partitioned the data on time, then for a given minute, all the calls will hit one partition. If you need to retrieve the data for a customer, then it will be a fan-out query because data may be distributed on all the partitions.
B: Senser1Value has only two values.
C: All the devices could have the same manufacturer.
Reference: https://docs.microsoft.com/en-us/azure/cosmos-db/sql/synthetic-partition-keys
