Azure Cosmos DB is Microsoft’s globally distributed, multi-model database service designed for scalable and high-performance modern applications. A key feature of Azure Cosmos DB is its integrated cache that can improve the performance of read-heavy workloads and can also reduce the total cost of ownership by reducing RU (request unit) consumption. In this post, we will discuss how to implement Azure Cosmos DB integrated cache and its benefits.
Understanding Azure Cosmos DB Integrated Cache
Integrated cache in Azure Cosmos DB is a server-side in-memory cache that provides a faster read of frequently accessed data. It operates at the server-side and caching is done on a per-partition key range basis. The same server-side cache is shared by all instances of the Azure Cosmos DB SDK.
Azure Cosmos DB integrated cache is available for all Cosmos accounts and enabled per container. The cache refresh interval can be set anywhere from 5 seconds to 2 hours.
Benefits of Integrated Cache
- Boosts Read Performance: By storing frequently accessed documents in memory, the integrated cache can boost the performance of read-heavy workloads. It has the capability to serve read requests directly from memory which is much faster than disk I/O operations.
- Reduces RU Consumption: RU (Request Unit) stands for the cost associated with both read and write operations. With integrated cache, you can make significant savings by reducing the RU charges resulting from read operations.
- Reduces Latency: Cached reads are served directly from memory, reducing network and disk latency.
Implementing Azure Cosmos DB integrated Cache
Below are the steps for enabling the cache.
- Navigate to the Azure portal and select your Azure Cosmos DB account.
- On the left side menu, under ‘Settings’, select ‘Cosmos DB features preview’.
- Under ‘Enable features’, select ‘Integrated cache’.
- Choose desired cache refresh interval and save your changes.
Once you have enabled the integrated cache, it will begin caching the data of the subsequent read operations that would take place.
Conclusion
Azure Cosmos DB’s integrated cache is a powerful feature that can enhance read performance and reduce costs associated with read operations. It’s a server-side feature that does not require any code changes and is worth considering for read-heavy workloads. Keep in mind that the benefits you get from caching highly depend on the cache hit rate. Proper monitoring and tuning of cache parameters are needed for obtaining optimal benefits.
Please note that currently, the integrated cache supports point read operations only. Queries, multi-partition reads are not cached. Another aspect is the cache does not support consistency stronger than session consistency.
By mastering these concepts, and how they relate to the DP-420: Designing and Implementing Native Applications Using Microsoft Azure Cosmos DB exam, you should have a solid foundation for demonstrating your skills in implementing caching with Azure Cosmos DB.
Practice Test
True or False: The Azure Cosmos DB integrated cache is a stage for transient caching of data separately from the actual database.
- True
- False
Answer: True
Explanation: The Azure Cosmos DB integrated cache is, indeed, a phase that temporarily caches data apart from the primary database. This helps boost performance and reduce costs.
In Azure Cosmos DB, what is the purpose of an integrated cache?
- A) For long-term storage
- B) To improve read latency
- C) To store user data
- D) None of the above
Answer: B) To improve read latency
Explanation: The main purpose of the integrated cache in Azure Cosmos DB is improving read latency, by caching data close to the application.
True or False: Integrated cache in Azure Cosmos DB can be manually turned off to save costs.
- True
- False
Answer: True
Explanation: You have the option to manually turn on and off the integrated cache in Azure Cosmos DB, depending on your requirements and to manage costs.
The Azure Cosmos DB integrated cache:
- A) Delays read-write operations
- B) Improves write latency
- C) Reduces read charges
- D) Increases operational costs
Answer: C) Reduces read charges
Explanation: The integrated cache within Azure Cosmos DB helps reduce read charges by caching data close to the application for quicker data read, hence saving costs.
True or False: The Azure Cosmos DB integrated cache can reduce provisioned throughput.
- True
- False
Answer: True
Explanation: By reducing the frequency of direct read operations from the database, the integrated cache can significantly reduce provisioned throughput.
In Azure Cosmos DB, can the integrated cache be used for SQL (Core) API?
- A) Yes
- B) No
Answer: A) Yes
Explanation: As of now, Azure Cosmos DB integrated cache can be used for SQL (Core) API for better read operations.
True or False: You need additional programming to use Azure Cosmos DB integrated cache with your existing Azure Cosmos DB accounts.
- True
- False
Answer: False
Explanation: Azure Cosmos DB integrated cache can be used without any changes to your application code. No additional programming is required.
Which statement is true about Azure Cosmos DB integrated cache?
- A) It is placed in the same region as your write region.
- B) It is designed to cache the entire database.
- C) It cannot be turned ON/OFF.
- D) It incurs extra costs for caching.
Answer: A) It is placed in the same region as your write region.
Explanation: The integrated cache is placed in the same Azure region as your write region by default to enable faster read operations.
True or False: Azure Cosmos DB integrated cache is designed for write-heavy workloads.
- True
- False
Answer: False
Explanation: The integrated cache is designed specifically for read-heavy workloads, not write-heavy ones. It reduces read latency and read charges for such workloads.
Which type of applications benefit the most from Azure Cosmos DB integrated cache?
- A) Applications with frequently updated data.
- B) Applications with read-heavy workloads.
- C) Applications with low data volume.
- D) Applications with high latency requirement.
Answer: B) Applications with read-heavy workloads.
Explanation: Azure Cosmos DB integrated cache is most beneficial for applications with read-heavy workloads. It reduces read latency and charges in such cases.
Interview Questions
What is Azure Cosmos DB integrated cache?
Azure Cosmos DB’s integrated cache allows the caching of frequently accessed data directly within the Cosmos DB. This provides an extra performance improvement by reducing the read latency and increasing throughput for the reads, while also reducing costs by decreasing the consumed RU/s.
What is the primary benefit of using Azure Cosmos DB integrated cache?
The primary benefit of using Azure Cosmos DB integrated cache is that it provides enhanced performance by reducing read latency and increasing throughput, all while reducing costs by decreasing the amount of RU/s consumed.
How is data partitioned in Azure Cosmos DB’s integrated cache?
Data partitioned in Azure Cosmos DB’s integrated cache follows the same partitioning scheme as your data in the Cosmos DB. This means that data cached from a particular logical partition will be cached together.
Does Azure Cosmos DB integrated cache affect write operations?
No, the integrated cache feature only affects read operations in Azure Cosmos DB. Write operations are unaffected and will continue to have consistency guarantees.
Can the integrated cache affect the data consistency level in Azure Cosmos DB?
No, the use of the integrated cache in Cosmos DB does not affect the selected consistency level. The cache obeys the set read consistency level on the client SDK.
How long does it take for data in Azure Cosmos DB’s integrated cache to get refreshed?
Data in Azure Cosmos DB’s integrated cache refresh every 5 seconds. However, this interval can be configured based on needs.
Can the caching feature impact the consumed RU/s cost with Azure Cosmos DB?
Yes, by using the integrated cache feature, you can reduce the RU/s consumed for read operations, which can, in turn, decrease the overall cost of operations with Cosmos DB.
Can the TTL (Time to Live) be set for data in Azure Cosmos DB’s integrated cache?
No, TTL settings in Azure Cosmos DB apply only to the main storage, not to the integrated cache.
What are some scenarios where Azure Cosmos DB’s integrated cache is not beneficial?
If your workload in Cosmos DB is write-heavy or your read operations don’t frequently access the same data, then the integrated cache may not provide you significant benefits.
Can users manually specify what data to cache in Azure Cosmos DB’s integrated cache?
No, users cannot manually specify what data to cache. Azure Cosmos DB’s integrated cache automatically caches data based on the read operations.
Does the integrated cache feature add any additional costs to Azure Cosmos DB?
No, the integrated cache feature is included in the cost of Azure Cosmos DB and does not incur any additional costs.
Can Azure Cosmos DB’s integrated cache be disabled?
Yes, Azure Cosmos DB’s integrated cache can be disabled if not needed. Disabling the cache does not impact the functioning of the Cosmos DB.
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