Cache Invalidation

Cache invalidation refers to the process of removing or updating cached data when the underlying data has changed. Caching is a commonly used technique in software development where frequently accessed data is stored in a temporary storage location, called a cache, to improve performance.

However, when the underlying data changes, the cached data may no longer be valid and can lead to incorrect results. Therefore, it is important to invalidate or update the cache to ensure that the data remains consistent with the updated information.

Here are a few real-world scenarios and examples of cache invalidation:

E-commerce website

Consider an e-commerce website that displays product prices on a product listing page. The prices are fetched from a database and cached to improve performance. If the price of a product is updated in the database, the cached price will be outdated and incorrect. Therefore, the cache needs to be invalidated or updated to reflect the latest price.

Example in Python:

2. Social media feed

Consider a social media platform that displays a user’s feed on their home page. The feed is generated based on the user’s friends and their posts, which are fetched from a database and cached to improve performance. If a friend makes a new post, the cached feed will be outdated and incorrect. Therefore, the cache needs to be invalidated or updated to reflect the latest posts.

Example in JavaScript:

In both examples, when new data is added or updated, the cache needs to be invalidated to ensure that the cached data remains consistent with the updated information. By doing so, the performance is maintained while ensuring data consistency.

Banking application

Consider a banking application that displays a customer’s account balance. The account balance is fetched from a database and cached to improve performance. If a transaction is made on the account, such as a deposit or withdrawal, the cached balance will be outdated and incorrect. Therefore, the cache needs to be invalidated or updated to reflect the latest balance.

Example in Java:

Weather application

Consider a weather application that displays the current temperature at a particular location. The temperature is fetched from a third-party API and cached to improve performance. If the temperature at the location changes, the cached temperature will be outdated and incorrect. Therefore, the cache needs to be invalidated or updated to reflect the latest temperature.

Example in Python:

In these examples, cache invalidation ensures that the cached data remains consistent with the updated information, ensuring accuracy and data integrity.

ASP.NET web application

Consider an ASP.NET web application that displays a list of products on a product listing page. The products are fetched from a database and cached to improve performance. If a new product is added to the database, the cached product list will be outdated and incorrect. Therefore, the cache needs to be invalidated or updated to reflect the latest product list.

Example in C#:

In this example, when a new product is added to the database, the cache for the product list needs to be invalidated to ensure that the cached data remains consistent with the updated information.

Windows Forms application

Consider a Windows Forms application that displays a list of customers in a DataGridView control. The customer data is fetched from a database and cached to improve performance. If a customer’s information is updated in the database, the cached customer data will be outdated and incorrect. Therefore, the cache needs to be invalidated or updated to reflect the latest customer data.

Example in C#:

In this example, when a customer’s information is updated in the database, the cache for the customer list needs to be invalidated to ensure that the cached data remains consistent with the updated information.

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