Hi, I'm Mikoo
Full-Stack Software Engineer & DevOps Specialist

-- Before: Slow query with multiple JOINs
SELECT u.name, p.title, c.content 
FROM users u 
JOIN posts p ON u.id = p.user_id 
JOIN comments c ON p.id = c.post_id 
WHERE u.active = 1 AND p.published = 1;

-- After: Optimized with proper indexing and filtering
SELECT u.name, p.title, c.content 
FROM users u USE INDEX(idx_active)
JOIN posts p USE INDEX(idx_user_published) ON u.id = p.user_id 
JOIN comments c USE INDEX(idx_post_id) ON p.id = c.post_id 
WHERE u.active = 1 AND p.published = 1
LIMIT 100;

-- Result: 80% faster execution time

// AWS Lambda function for processing device status
exports.handler = async (event) => {
    const sqs = new AWS.SQS();
    const cloudwatch = new AWS.CloudWatch();
    
    try {
        // Process SQS messages from IoT devices
        const messages = JSON.parse(event.Records[0].body);
        
        for (const message of messages) {
            const { deviceId, status, timestamp, metrics } = message;
            
            // Log device health metrics
            await cloudwatch.putMetricData({
                Namespace: 'IoT/DeviceHealth',
                MetricData: [{
                    MetricName: 'DeviceStatus',
                    Value: status === 'online' ? 1 : 0,
                    Unit: 'Count',
                    Dimensions: [{
                        Name: 'DeviceId',
                        Value: deviceId
                    }]
                }]
            }).promise();
            
            // Handle offline devices
            if (status === 'offline') {
                await handleOfflineDevice(deviceId, timestamp);
            }
        }
        
        return { statusCode: 200, body: 'Success' };
    } catch (error) {
        console.error('Error processing device status:', error);
        return { statusCode: 500, body: 'Error' };
    }
};

// High-performance API endpoint with caching
[ApiController]
[Route("api/[controller]")]
public class DeviceController : ControllerBase
{
    private readonly IMemoryCache _cache;
    private readonly IDeviceService _deviceService;
    
    public DeviceController(IMemoryCache cache, IDeviceService deviceService)
    {
        _cache = cache;
        _deviceService = deviceService;
    }
    
    [HttpGet("{id}")]
    public async Task<IActionResult> GetDevice(int id)
    {
        var cacheKey = $"device_{id}";
        
        if (!_cache.TryGetValue(cacheKey, out DeviceDto device))
        {
            device = await _deviceService.GetDeviceAsync(id);
            
            if (device != null)
            {
                _cache.Set(cacheKey, device, TimeSpan.FromMinutes(5));
            }
        }
        
        return device != null ? Ok(device) : NotFound();
    }
    
    [HttpPost("batch-update")]
    public async Task<IActionResult> BatchUpdateDevices(
        [FromBody] List<DeviceUpdateDto> updates)
    {
        var result = await _deviceService.BatchUpdateAsync(updates);
        
        // Invalidate cache for updated devices
        foreach (var update in updates)
        {
            _cache.Remove($"device_{update.Id}");
        }
        
        return Ok(result);
    }
}

#!/bin/bash
# Automated deployment script for Raspberry Pi fleet

DEPLOY_DIR="/opt/digital-signage"
BACKUP_DIR="/opt/backups"
APP_NAME="signage-app"

echo "Starting deployment process..."

# Create backup of current version
if [ -d "$DEPLOY_DIR" ]; then
    sudo cp -r $DEPLOY_DIR $BACKUP_DIR/$(date +%Y%m%d_%H%M%S)
    echo "Backup created"
fi

# Download and extract new version
wget -O /tmp/app.tar.gz "$DEPLOY_URL"
sudo tar -xzf /tmp/app.tar.gz -C $DEPLOY_DIR

# Install dependencies
cd $DEPLOY_DIR
npm install --production

# Update PM2 configuration
sudo pm2 delete $APP_NAME 2>/dev/null || true
sudo pm2 start ecosystem.config.js
sudo pm2 save

# Health check
sleep 10
if sudo pm2 list | grep -q "online.*$APP_NAME"; then
    echo "Deployment successful!"
    # Clean up old backups (keep last 5)
    ls -t $BACKUP_DIR | tail -n +6 | xargs -r rm -rf
else
    echo "Deployment failed, rolling back..."
    # Rollback logic here
    exit 1
fi