20 Caching Interview Questions and Answers

If you are interviewing for a position that involves working with caching, it is important to be prepared to answer questions about this topic. Caching is a process of storing data in a temporary location so that it can be quickly accessed later. Employers will want to know if you are familiar with different caching techniques and how to implement them. In this article, we review some common caching questions that you may encounter during your job interview.

Caching Interview Questions and Answers

Here are 20 commonly asked Caching interview questions and answers to prepare you for your interview:

1. What is caching?

Caching is a technique that is used in order to improve the performance of a system. When data is cached, it is stored in a temporary location in order to be accessed more quickly the next time that it is needed. Caching is often used in web browsers in order to improve the speed at which pages load.

2. What are some common types of caches used in computer systems?

Some common types of caches used in computer systems are CPU caches, disk caches, and web caches. CPU caches are used to store frequently accessed data in memory so that it can be quickly accessed by the CPU. Disk caches are used to store frequently accessed data on the disk so that it can be quickly accessed by the disk drive. Web caches are used to store frequently accessed data on the web so that it can be quickly accessed by the web browser.

3. Can you explain what the “cache hit” and “cache miss” terms mean in a caching system?

A cache hit occurs when a requested item is found in the cache. A cache miss occurs when a requested item is not found in the cache.

4. How does caching help improve performance in software applications?

Caching helps improve performance by storing data in a temporary location so that it can be quickly accessed the next time it is needed. When data is cached, it is stored in memory or on a disk so that it can be accessed more quickly the next time it is needed. Caching is often used to improve the performance of web applications by storing data such as web pages or images in a cache so that they can be quickly accessed the next time they are needed.

5. How do you make sure that your caching strategy doesn’t increase latency or cause other problems for end users?

There are a few things to keep in mind when designing a caching strategy. First, you need to make sure that your cache is large enough to hold all the data you need it to, but not so large that it causes delays in retrieving data. Second, you need to design your cache so that it can be quickly and easily updated when new data is available. Finally, you need to make sure that your caching strategy is compatible with the rest of your system so that it doesn’t cause any unexpected problems.

6. What are different ways to cache data when using a relational database?

There are a few different ways that you can cache data when using a relational database. One way is to use a materialized view, which is a cached copy of the data that is updated periodically. Another way is to use a cache table, which is a table that is populated with data from the database that is then used to serve requests. Finally, you can use a caching proxy, which is a server that sits between the database and the application and caches data as it is requested.

7. What’s the difference between client-side and server side caching?

Client-side caching is when the client stores data locally so that it can be accessed faster the next time it is needed. Server-side caching is when the server stores data locally so that it can be accessed faster the next time it is needed.

8. What is the difference between read-through and write-through in the context of caching?

Read-through caching is when the cache is populated with data from the backing store as it is needed. Write-through caching is when data is written to both the cache and the backing store at the same time.

9. What is eviction in the context of caching?

Eviction is the process of removing data from a cache when it is no longer needed. This can happen for a variety of reasons, but typically has to do with the cache being full and needing to make room for new data. When data is evicted from a cache, it is typically moved to a slower storage medium so that it can still be accessed if needed, but is not taking up valuable space in the cache.

10. Can you explain how TTL (time-to-live) works in caching?

TTL is a value that is assigned to a cached item, which dictates how long that item is allowed to stay in the cache before it is considered expired and is purged. The TTL is set by the cache owner, and can be based on any time frame that makes sense for the particular cached item.

11. What is fragmentation in the context of caching?

Fragmentation is the process of breaking up data into smaller pieces so that it can be stored more efficiently. When data is stored in a cache, it is often stored in a fragmented state in order to save space. This can sometimes lead to problems if the data needs to be accessed again later, as the pieces may need to be reassembled in order to be used.

12. What are invalidations in the context of caching?

Invalidations are a type of cache management where the cached data is no longer considered valid and needs to be updated. This can be done in a number of ways, but is typically done either by setting a time limit on the cached data so that it expires after a certain amount of time, or by invalidating the cache whenever the data that it is based on is updated.

13. Why is it important to have an expiration policy with caching?

An expiration policy is important with caching because it helps to ensure that the data that is being cached is still relevant and accurate. If data is cached for too long, it runs the risk of becoming outdated and inaccurate, which can lead to problems down the road. By setting an expiration policy, you can help to ensure that the data being cached is still fresh and up-to-date.

14. What do you understand about lazy loading in the context of caching?

Lazy loading is a caching technique where data is only loaded into memory when it is needed. This can help improve performance by reducing the amount of data that needs to be loaded into memory upfront.

15. What are the various factors that affect the choice of a caching solution?

There are many factors that can affect the choice of a caching solution, including the size of the data set, the frequency of updates, the read/write ratio, the access patterns, the hardware constraints, and the budget.

16. Is there any way to tell if a particular item has been cached or not? If yes, then how?

There is no foolproof way to tell if an item has been cached, but there are a few methods that can be used to make an educated guess. One way is to check the response headers from the server. If the headers indicate that the content has been cached, then it is likely that the item has been cached. Another way to check is to try to access the item from a different browser or computer. If the item loads quickly, then it is likely that it has been cached.

17. What is your opinion on HTTPS cache headers?

HTTPS cache headers are a great way to improve the performance of a website. By caching resources on a user’s browser, the website can avoid having to send requests to the server for each page load. This can speed up the website’s performance, especially for users with slow internet connections.

18. What is object pooling in the context of caching?

Object pooling is a caching technique where objects are reused instead of being recreated each time they are needed. This can improve performance by reducing the amount of time spent creating new objects. When using object pooling, it is important to make sure that the objects being reused are still valid and that they are properly cleaned up before being reused again.

19. Do you think that caching can lead to consistency issues? If yes, then what measures would you take to avoid such issues?

Yes, caching can lead to consistency issues if not managed properly. In order to avoid these issues, it is important to have a clear understanding of what data is being cached and how often it is being accessed. Additionally, measures should be taken to ensure that the data being cached is consistent across all devices and platforms.

20. What challenges do you think developers face when implementing caching strategies?

Developers face a number of challenges when implementing caching strategies, chief among them being deciding what data to cache and for how long. Other challenges include ensuring that cached data is consistent with the source data, and dealing with the potential for cache invalidation.