Does storing personal data in Redis create UK GDPR issues?

Redis is an in-memory cache with optional persistence. UK GDPR Article 25 data minimisation: only cache the minimum personal data necessary for the specific function (e.g., session ID + user ID + role — not the full user profile). TTL (Time To Live): set a maximum TTL on any cache entry containing personal data (session expiry). AWS ElastiCache encryption at rest and in transit satisfies UK GDPR Article 32 security requirement for cached data.

How do we handle UK GDPR right to erasure with Redis cache?

Right to erasure: when a user account is deleted, delete all Redis cache entries containing that user's personal data. Pattern: user ID as cache key prefix (user:{id}:session, user:{id}:preferences) — DEL user:{id}:* deletes all user-specific cache. Session store: invalidate all sessions for the deleted user (Redis SCAN + DEL by user ID prefix). Most TTL-based caches expire naturally within hours/days — but immediate erasure on request is required by UK GDPR.

Redis Vs Memcached Vs Dynamodb Dax Uk

Redis vs Memcached vs DynamoDB DAX — Which Cache for UK Software? (2025)

Updated: July 20259 min read

🇬🇧 UK💷 GBP📊 Comparison🔒 UK GDPR⚖️ UK Law

Direct Answer

Redis (AWS ElastiCache for Redis) is the right default for UK software projects: rich data structures beyond simple key-value (sorted sets, streams, pub/sub), Lua scripting, and built-in persistence options. Memcached is for simpler pure key-value caching where Redis's feature set is not needed. DynamoDB DAX is for DynamoDB-specific read acceleration only — not a general-purpose cache. Caching layer choice affects performance, UK GDPR personal data handling in cache, and Cyber Essentials patching obligations. Here is a UK-focused comparison.

Factor	Redis (ElastiCache)	Memcached (ElastiCache)	DynamoDB DAX
UK GDPR personal data	⚠️ Encrypted at rest (ElastiCache) + TTL for retention	⚠️ Encrypted at rest — simpler config	⚠️ Encrypted — DynamoDB policies apply
Cyber Essentials (managed)	✅ ElastiCache — AWS managed patching	✅ ElastiCache — AWS managed	✅ AWS managed
Data structures	✅ Strings, hashes, lists, sets, sorted sets, streams	Strings only	DynamoDB item structure only
Session storage	✅ Standard — fast, with TTL	✅ Simple sessions	Not appropriate
Rate limiting	✅ INCR + TTL — standard pattern	Possible but less natural	Not appropriate
Pub/Sub messaging	✅ Redis Pub/Sub	Not supported	Not supported
UK data residency	✅ eu-west-2 (ElastiCache)	✅ eu-west-2	✅ eu-west-2
DynamoDB read acceleration	Not applicable	Not applicable	✅ Only use case — microsecond reads
ClickMasters default	✅ Sessions, rate limiting, queues, leaderboards	Simple key-value only	DynamoDB-specific only