Caching.

Cache strategies across the stack — HTTP, CDN, Redis, browser, memoization, and invalidation patterns. Covers 9 sub-skills.

• Caching · 1 of 3

  Redis Caching Patterns

  Which Redis command removes a key and its associated value?

  ADROPBREMOVECCLEARDDEL

• Caching · 2 of 3

  Cache-Aside, Write-Through, Write-Behind

  A lookup finds a key in neither the cache nor the database (the read returns null). Under negative caching, what happens next?

  Araised key absent errorBstored full payload valueCstored sentinel for missDskipped cache for null

• Caching · 3 of 3

  Stale-While-Revalidate & SWR

  How does TanStack Query's structural sharing optimize re-renders when data is refetched?

  AIt compresses the data structure to use less memoryBIt shares the query function between multiple componentsCIt preserves referential identity for unchanged parts of the dataDIt splits the data across multiple cache entries for parallel access