# Neon Database Optimization Guide

This document provides specific recommendations for optimizing database connections when using Neon PostgreSQL.

## Current Issues Observed

From your logs, we can see:

```
Can't reach database server at `ep-tiny-math-a2zsshve-pooler.eu-central-1.aws.neon.tech:5432`
[NODE-CRON] [WARN] missed execution at Sun Jun 29 2025 12:00:00 GMT+0200! Possible blocking IO or high CPU
```

## Root Causes

### 1. Neon Connection Limits

- **Free Tier**: 20 concurrent connections
- **Pro Tier**: 100 concurrent connections
- **Multiple schedulers** can quickly exhaust connections

### 2. Connection Pooling Issues

- Each scheduler was creating separate PrismaClient instances
- No connection reuse between operations
- No retry logic for temporary failures

### 3. Neon-Specific Challenges

- **Auto-pause**: Databases pause after inactivity
- **Cold starts**: First connection after pause takes longer
- **Regional latency**: eu-central-1 may have variable latency

## Solutions Implemented

### 1. Fixed Multiple PrismaClient Instances ✅

```typescript
// Before: Each file created its own client
const prisma = new PrismaClient(); // ❌

// After: All use singleton
import { prisma } from "./prisma.js"; // ✅
```

### 2. Added Connection Retry Logic ✅

```typescript
// Automatic retry for connection errors
await withRetry(async () => await databaseOperation(), {
  maxRetries: 3,
  initialDelay: 2000,
  maxDelay: 10000,
  backoffMultiplier: 2,
});
```

### 3. Enhanced Connection Pooling ✅

```typescript
// Production-ready pooling with @prisma/adapter-pg
USE_ENHANCED_POOLING = true;
DATABASE_CONNECTION_LIMIT = 20;
DATABASE_POOL_TIMEOUT = 10;
```

## Neon-Specific Configuration

### Environment Variables

```bash
# Optimized for Neon
DATABASE_URL="postgresql://user:pass@ep-tiny-math-a2zsshve-pooler.eu-central-1.aws.neon.tech:5432/db?sslmode=require&connection_limit=15"

# Connection pooling (leave some headroom for manual connections)
DATABASE_CONNECTION_LIMIT=15  # Below Neon's 20 limit
DATABASE_POOL_TIMEOUT=30      # Longer timeout for cold starts
USE_ENHANCED_POOLING=true     # Enable for better resource management

# Scheduler intervals (reduce frequency to avoid overwhelming)
CSV_IMPORT_INTERVAL="*/30 * * * *"    # Every 30 minutes instead of 15
IMPORT_PROCESSING_INTERVAL="*/10 * * * *"  # Every 10 minutes instead of 5
SESSION_PROCESSING_INTERVAL="0 */2 * * *"  # Every 2 hours instead of 1
```

### Connection String Optimization

```bash
# Add these parameters to your DATABASE_URL
?sslmode=require                    # Required for Neon
&connection_limit=15                # Explicit limit
&pool_timeout=30                    # Connection timeout
&connect_timeout=10                 # Initial connection timeout
&application_name=livedash-scheduler # For monitoring
```

## Monitoring & Troubleshooting

### 1. Health Check Endpoint

```bash
# Check connection health
curl -H "Authorization: Bearer your-token" \
     http://localhost:3000/api/admin/database-health
```

### 2. Neon Dashboard Monitoring

- Monitor "Active connections" in Neon dashboard
- Check for connection spikes during scheduler runs
- Review query performance and slow queries

### 3. Application Logs

```bash
# Look for connection patterns
grep "Database connection" logs/*.log
grep "pool" logs/*.log
grep "retry" logs/*.log
```

## Performance Optimizations

### 1. Reduce Scheduler Frequency

```typescript
// Current intervals may be too aggressive
CSV_IMPORT_INTERVAL = "*/15 * * * *"; // ➜ "*/30 * * * *"
IMPORT_PROCESSING_INTERVAL = "*/5 * * * *"; // ➜ "*/10 * * * *"
SESSION_PROCESSING_INTERVAL = "0 * * * *"; // ➜ "0 */2 * * *"
```

### 2. Batch Size Optimization

```typescript
// Reduce batch sizes to avoid long-running transactions
CSV_IMPORT_BATCH_SIZE = 50; // ➜ 25
IMPORT_PROCESSING_BATCH_SIZE = 50; // ➜ 25
SESSION_PROCESSING_BATCH_SIZE = 20; // ➜ 10
```

### 3. Connection Keepalive

```typescript
// Keep connections warm to avoid cold starts
const prisma = new PrismaClient({
  datasources: {
    db: {
      url: process.env.DATABASE_URL + "&keepalive=true",
    },
  },
});
```

## Troubleshooting Common Issues

### "Can't reach database server"

**Causes:**

- Neon database auto-paused
- Connection limit exceeded
- Network issues

**Solutions:**

1. Enable enhanced pooling: `USE_ENHANCED_POOLING=true`
2. Reduce connection limit: `DATABASE_CONNECTION_LIMIT=15`
3. Implement retry logic (already done)
4. Check Neon dashboard for database status

### "Connection terminated"

**Causes:**

- Idle connection timeout
- Neon maintenance
- Long-running transactions

**Solutions:**

1. Increase pool timeout: `DATABASE_POOL_TIMEOUT=30`
2. Add connection cycling
3. Break large operations into smaller batches

### "Missed cron execution"

**Causes:**

- Blocking database operations
- Scheduler overlap
- High CPU usage

**Solutions:**

1. Reduce scheduler frequency
2. Add concurrency limits
3. Monitor scheduler execution time

## Recommended Production Settings

### For Neon Free Tier (20 connections)

```bash
DATABASE_CONNECTION_LIMIT=15
DATABASE_POOL_TIMEOUT=30
USE_ENHANCED_POOLING=true
CSV_IMPORT_INTERVAL="*/30 * * * *"
IMPORT_PROCESSING_INTERVAL="*/15 * * * *"
SESSION_PROCESSING_INTERVAL="0 */3 * * *"
```

### For Neon Pro Tier (100 connections)

```bash
DATABASE_CONNECTION_LIMIT=50
DATABASE_POOL_TIMEOUT=20
USE_ENHANCED_POOLING=true
CSV_IMPORT_INTERVAL="*/15 * * * *"
IMPORT_PROCESSING_INTERVAL="*/10 * * * *"
SESSION_PROCESSING_INTERVAL="0 */2 * * *"
```

## Next Steps

1. **Immediate**: Apply the new environment variables
2. **Short-term**: Monitor connection usage via health endpoint
3. **Long-term**: Consider upgrading to Neon Pro for more connections
4. **Optional**: Implement read replicas for analytics queries

## Monitoring Checklist

- [ ] Check Neon dashboard for connection spikes
- [ ] Monitor scheduler execution times
- [ ] Review error logs for connection patterns
- [ ] Test health endpoint regularly
- [ ] Set up alerts for connection failures

With these optimizations, your Neon database connections should be much more stable and efficient!