fiddy/docs/POSTGRES_TO_REDIS_RATELIMITTING_MIGRATION_REFERENCE.md

Postgres to Redis Rate Limiting Migration Reference

Overview

This document provides guidance for migrating API rate limiting from Postgres to Redis in the Fiddy Finance Buddy App. It covers:

• Rate limiting tiers and keying strategies
• Migration triggers and operational considerations
• Redis setup, scaling, monitoring, and best practices
• Example config (not enabled by default)

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Rate Limiting Tiers & Keying

• Auth endpoints (login/register): Strict limits per IP and identifier (email)
• Write endpoints (POST/PUT/DELETE): Moderate limits per user and IP
• Read endpoints (GET): Higher limits per user and IP
• Keying:
  • Unauthenticated: IP only
  • Auth endpoints: IP + email
  • Authenticated: user ID + IP

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Migration Triggers

Switch to Redis if:

• API request volume or burst traffic causes DB contention or latency
• Postgres rate limit table grows rapidly or cleanup becomes burdensome
• You need native TTL, atomic counters, or horizontal scaling

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Redis Management & Planning

Setup

• Provision Redis (self-hosted or managed)
• Secure networking, secrets, and access control
• Integrate Redis client in backend (e.g., ioredis or redis npm package)

Scaling

• Monitor memory usage, eviction policy, and connection pools
• Use Redis clustering/replication for high availability

Monitoring

• Set up alerting for latency, memory, and connection errors
• Track rate limit key usage and eviction

TTL & Data Retention

• Use Redis native TTL for expiring rate limit keys
• No manual cleanup required

Backup

• Backups are optional for rate limit counters
• Focus on monitoring and HA

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Example Redis Config (Not Enabled by Default)

docker-compose.yml (add, but comment out)

# redis:
#   image: redis:7
#   ports:
#     - "6379:6379"
#   restart: unless-stopped

.env.example

# REDIS_URL=redis://localhost:6379

Node.js Integration Example

// ...existing code...
// import Redis from 'ioredis';
// const redis = new Redis(process.env.REDIS_URL);
// ...existing code...

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Best Practices

• Document migration triggers in backend guidance
• Keep Redis config ready but disabled until needed
• Reference this doc in PROJECT_INSTRUCTIONS.md for future backend work

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References

• Redis Official Docs
• ioredis npm package
• Rate limiting patterns

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Last updated: 2026-02-09