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Usually, no. A function name describes code; a cache key identifies the particular data stored. Choose the key from the trusted identifiers and other dimensions that distinguish the result—not from the routine that happens to retrieve or create it.
“Memory key” is not a standard term established for a particular language or runtime here. This article uses it to mean a cache key. The same principles apply to another persistent store only if it uses keys with similar identity rules.
What does a cache key identify?
A cache key is the identifier an application uses to store and retrieve a cached value. Microsoft’s HybridCache guidance says: “The key passed to GetOrCreateAsync must uniquely identify the data being cached.” The caller is responsible for choosing a scheme that does not confuse one value with another.
A routine name alone rarely establishes that identity. A function such as load_preferences might return different preferences for different users; get_order might retrieve different orders. If the key omits a dimension that changes the result, distinct values can be treated as the same cached item.
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How should you compose a key?
Start with the source identifiers that determine the value, then include any additional dimensions that make results distinct. Microsoft’s examples use composite keys, such as a region together with an order ID. A preferences cache might use a trusted user identifier and the preference scope.
- Order: a key could combine region and order ID when both distinguish the order.
- User preferences: a key could combine a trusted user ID with a preference category, for example
user_prefs_<trusted-user-id>.
These are patterns, not universal formats. Choose components based on the data model and what changes the result. The routine label may change during refactoring while the underlying order or preference identity stays the same; that is a design implication of the uniqueness requirement, not a guarantee about every cache implementation.
What should you check before using a key?
- Identity: Which source identifiers determine the value?
- Result dimensions: What other inputs or context can change the result, such as region or preference scope?
- Collision risk: Could two distinct values produce the same key under the chosen scheme?
- Input trust: Can untrusted input create arbitrary keys?
- Recovery: What happens when the entry is missing, expired, deleted, or lost?
Why avoid raw external input as a key?
Microsoft advises against using external user input directly as a cache key. Its HybridCache security guidance notes risks including unauthorized access and denial of service if an attacker floods the cache with random or meaningless keys. Validate and constrain inputs, and build keys from trusted identity and explicitly supported dimensions rather than accepting arbitrary key strings from a request.
What happens when a cache entry is missing?
A cache is not the authoritative source of the value. Entries may expire or be deleted, and cached data can be lost on restart or failover depending on the cache configuration. Microsoft’s in-memory caching guidance recommends a fallback when a value is unavailable; the application should be able to retrieve or recompute the data from its source and then continue.
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Expiration and deletion are normal parts of cache management, as described in the Azure Caching Guidance. Therefore, application correctness should not depend on a particular cache entry remaining present.
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Does local or distributed caching change the key rule?
No: the key still needs to identify the cached data. Deployment does affect where entries are available and how consistently application instances see them. Microsoft’s ASP.NET Core guidance explains that a web farm using non-sticky sessions needs a distributed cache to avoid cache consistency problems. A process-local cache is not shared across instances, so an application’s deployment and session model matter when selecting the cache architecture.
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