Preferences Cache

Cache Redis 7 Residency: us-east-1 Retention: 30d In-Memory User Preferences

Overview

Redis cache for user notification preferences, reducing database queries and improving notification processing latency.

Caching Strategy

User Preferences

  • Notification Settings: Channel preferences per notification type
  • Quiet Hours: Do-not-disturb schedules
  • Muted Entities: Temporarily muted tasks/projects
  • Delivery Methods: Email, push, Slack preferences

Cache Duration

  • User Preferences: 1-hour TTL
  • Quiet Hours: 24-hour TTL
  • Muted List: 15-minute TTL
  • Unsubscribe List: 1-hour TTL

Technical Details

Specifications:

  • Version: Redis 7.x
  • Memory: 8 GB
  • Persistence: RDB snapshots every 15 minutes
  • Replication: Primary with 1 read replica
  • Clustering: Single instance (small dataset)

Performance:

  • Latency: P99 < 1ms
  • Throughput: 50,000 ops/second
  • Hit Rate: Target 95%+
  • Connections: Max 1,000

Data Structures

User Preferences

prefs:user:{user_id} -> Preferences object (hash)
  - email_enabled: true
  - push_enabled: true
  - slack_enabled: false
  - digest_frequency: daily
  - quiet_hours_start: 22:00
  - quiet_hours_end: 08:00
TTL: 1 hour

Muted Entities

muted:{user_id} -> Set of muted entity IDs (set)
  - task:123
  - project:456
TTL: 15 minutes

Unsubscribe Tokens

unsub:{token} -> User ID and notification type (string)
TTL: 7 days

Cache Invalidation

🔄 Preference Updates

Cache invalidated immediately when users change preferences.

  • Preference Update: Immediate cache invalidation
  • Mute/Unmute: Clear muted entities cache
  • Unsubscribe: Clear preference cache
  • TTL Fallback: Automatic refresh after TTL

Monitoring

  • Memory Usage: Alert at 75% capacity
  • Hit Rate: Alert if < 90%
  • Eviction Rate: Track unexpected evictions
  • Replication Lag: Monitor replica sync

Security

  • Authentication: Redis AUTH enabled
  • TLS: Encrypted connections
  • Network: Private VPC only
  • Data Sensitivity: Low (preferences only)
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