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skills/implementing-query-caching/references/redis-configuration.md

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+# Redis Configuration
+
+## Connection Setup
+
+**ioredis client with connection pooling:**
+
+```typescript
+import { Redis } from 'ioredis'
+
+const redis = new Redis({
+  host: process.env.REDIS_HOST || 'localhost',
+  port: parseInt(process.env.REDIS_PORT || '6379'),
+  password: process.env.REDIS_PASSWORD,
+  db: parseInt(process.env.REDIS_DB || '0'),
+  maxRetriesPerRequest: 3,
+  retryStrategy: (times) => {
+    const delay = Math.min(times * 50, 2000)
+    return delay
+  },
+  lazyConnect: true,
+})
+
+redis.on('error', (err) => {
+  console.error('Redis connection error:', err)
+})
+
+redis.on('connect', () => {
+  console.log('Redis connected')
+})
+
+export default redis
+```
+
+## Serverless Considerations
+
+**Redis in serverless environments (Vercel, Lambda):**
+
+- Use Redis connection pooling (ioredis handles this)
+- Consider Upstash Redis (serverless-optimized)
+- Set `lazyConnect: true` to avoid connection on module load
+- Handle cold starts gracefully (fallback to database)
+- Monitor connection count to avoid exhaustion
+
+**Upstash example:**
+
+```typescript
+import { Redis } from '@upstash/redis'
+
+const redis = new Redis({
+  url: process.env.UPSTASH_REDIS_REST_URL,
+  token: process.env.UPSTASH_REDIS_REST_TOKEN,
+})
+```
+
+Upstash uses HTTP REST API, avoiding connection pooling issues in serverless.
+
+## Cache Implementation Checklist
+
+When implementing caching:
+
+**Setup:**
+- [ ] Redis client configured with connection pooling
+- [ ] Error handling for Redis connection failures
+- [ ] Fallback to database when Redis unavailable
+- [ ] Environment variables for Redis configuration
+
+**Cache Keys:**
+- [ ] Consistent key naming convention (entity:identifier)
+- [ ] Hash complex query parameters for deterministic keys
+- [ ] Namespace keys by entity type
+- [ ] Document key patterns
+
+**Caching Logic:**
+- [ ] Cache-aside pattern (read from cache, fallback to DB)
+- [ ] Serialize/deserialize with JSON.parse/stringify
+- [ ] Handle null/undefined results appropriately
+- [ ] Log cache hits/misses for monitoring
+
+**Invalidation:**
+- [ ] Invalidate on create/update/delete mutations
+- [ ] Handle cascading invalidation for related entities
+- [ ] Consider bulk invalidation for list queries
+- [ ] Test invalidation across all mutation paths
+
+**TTL Configuration:**
+- [ ] Define TTL for each data type
+- [ ] Shorter TTL for frequently changing data
+- [ ] Longer TTL for static/rarely changing data
+- [ ] Document TTL choices and rationale
+
+**Monitoring:**
+- [ ] Track cache hit rate
+- [ ] Monitor cache memory usage
+- [ ] Log invalidation events
+- [ ] Alert on Redis connection failures