Cache key

As explained in Latency

A cache key is an identifier derived from a request or function input that selects a corresponding cached result.

A cache key is an identifier that selects the cached value associated with a request or function input. A hit returns that value; a missing or expired key produces a miss requiring retrieval from the backing store. section 6.2 section 6.3.1

In a cache-aside workflow:

• The application looks up the cache using the key. section 6.3.1
• A hit returns the associated value directly. section 6.3.1
• A miss causes the application to query the backing store, transform the result, and store it under the same key. section 6.3.1

User information keyed by user ID

An application uses a user ID as the cache key, queries the database when the key is absent, converts the returned user information to JSON, and stores that JSON under the ID. section 6.3.1

Figure 6.1 With cache-aside caching, the client first looks up a key from the cache. On a cache miss, the client queries the database and updates the cache.

The cache-aside sequence shows the key lookup, database fallback, and cache update after a miss. section 6.3.1

How Latency covers it

How deep it goes

Explains hits, misses, expiration, cache updates, and hit-to-miss measurement through a cache-aside workflow.

Examples

Uses user IDs as keys for JSON-encoded user information and illustrates database fallback after a miss.

What it assumes

Assumes an application, cache, and backing store, while defining cache hits, misses, and key-based lookup directly.

What you can do after

Apply cache-aside caching by choosing a lookup key, handling misses, querying the backing store, and updating the cache.

How it connects

Connects cache hits, cache misses, cache-aside caching, backing stores, negative caching, and cache replacement policies.

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Also explained in

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  liveBookmanning.com
  Building Web APIs with ASP.NET CoreA cache key is an identifier that distinguishes a cached entry associated with a particular request or data variant.
• 

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  GitHub Actions in Action: Continuous integration and delivery for DevOpsA cache key is an identifier that determines which stored cache entry a request retrieves or replaces.

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Related concepts

• cachingused by · Caching is the practice of storing reusable data or computation results so later access can avoid repeating retrieval or computation.
• memoizationused by · Memoization is an optimization technique that stores computation results with their inputs so equivalent later evaluations can reuse them without recomputation.
• hash valueproduces · A hash value is a deterministic, typically fixed-size value produced by applying a hash function to input data, often for lookup, comparison, identification, or integrity checking.
• generationconfigures · Generation is the computational production of outputs from supplied inputs or context, often by applying a model to produce predictions or new content.

This explainer was generated by Manning's knowledge graph from the text of Latency. The section links point to the parts of the book it draws on.