How Pre-Caching Works?

Here’s a step-by-step explanation of how pre-caching works in system design:

Step 1: Fetch

• The first step involves identifying the resources that are frequently accessed or are critical for the system’s performance.
• When a user requests a resource, such as a webpage or an image, the system initiates a request to fetch the data.
• If the requested data is already present in the cache and is valid (not expired), the system proceeds to serve it directly from the cache, skipping the need to fetch it from the database.

Step 2: Pre-cache

• While serving the requested data to the user, the system anticipates future requests for similar data.
• It proactively identifies frequently accessed or critical data and pre-loads it into the cache, even before it’s requested by users. This pre-cached data remains readily available in the cache, reducing the need for repeated database queries.
• Based on the identified resources, a caching strategy is chosen. This could involve determining the appropriate caching mechanism such as browser caching, server-side caching, or content delivery networks (CDNs).
• Once the caching strategy is defined, the system implements prefetching or preloading mechanisms to fetch the identified resources proactively. This could involve fetching resources in the background before they are actually requested by the user, based on historical usage patterns or predictive algorithms.

Step 3: Check Cache

• When a new request for data comes in, the system first checks the cache to see if the requested data is available. If the data is found in the cache and is still valid, it’s served directly from the cache, avoiding the need to fetch it from the database. This helps in reducing latency and improves overall system performance.
• The fetched resources are stored locally or in a faster storage medium, such as memory cache or solid-state drives (SSDs), depending on the caching strategy selected. The storage allocation is optimized to ensure quick access to the cached resources when needed.
• To ensure the freshness of cached data and prevent stale content, expiration and refresh policies are defined. Cached resources are periodically checked for expiration, and if necessary, they are refreshed or invalidated to fetch the latest version from the origin server.

Step 4: Get from Database

• If the requested data is not found in the cache or is expired, the system fetches it from the database. Once retrieved from the database, the data is stored in the cache for future requests.
• Subsequent requests for the same data can then be served directly from the cache, minimizing the need for frequent database queries.
• The system continuously monitors and manages the cache to optimize resource utilization and performance. This includes eviction policies to remove least-used resources from the cache, as well as cache warming techniques to pre-load the cache during off-peak hours.

Pre-caching is like getting ready for something before it happens.

Imagine you’re going on a trip and you pack your bag the night before so you’re all set to go in the morning.

That’s pre-caching! In the digital world, it’s when your device stores information ahead of time, like loading a webpage before you even click on it. This helps things run smoother and faster, saving you time and frustration. So, pre-caching is a handy trick that improves your online experience.