504 504 Gateway Timeout

-- Identify slow queries in PostgreSQL
SELECT query, calls, total_time / calls AS avg_time
FROM pg_stat_statements
ORDER BY avg_time DESC
LIMIT 10

-- Add missing indexes
CREATE INDEX idx_users_email ON users(email);

-- Use query optimization techniques
EXPLAIN ANALYZE SELECT * FROM orders WHERE user_id = 123;

# Nginx — longer upstream timeout
location /api/ {
  proxy_pass http://backend;
  proxy_read_timeout 120s;
  proxy_connect_timeout 30s;
}

# Or move long operations to background jobs
// Instead of processing inline:
const result = await processLargeFile(file)
res.json(result)

// Use a job queue:
const job = await queue.add('process-file', { fileId })
res.status(202).json({ jobId: job.id })