How would you fix a situation where the database has grown and started to slow down?

First, I will analyze the database state using monitoring tools and logs. I will identify slow queries and problematic areas.

Next, the following steps are possible:

• Query optimization:
  • Refactoring SQL queries to reduce the number of reads and writes.
  • Avoiding N+1 queries on the frontend by loading related data at once.
  • Using appropriate data types.
• Indexing:
  • Creating or optimizing indexes for frequently used columns.
  • Removing unused indexes.
• Caching:
  • Implementing caching on the frontend side (using libraries like React Query, SWR) or backend (Redis, Memcached) for frequently requested but rarely changing data.
• Scaling:
  • Vertical scaling: increasing server resources (CPU, memory, disk).
  • Horizontal scaling: sharding (dividing data across multiple servers) or replication (creating copies of the database).
• Denormalization:
  • Partial denormalization of the database structure to speed up reads if justified.
• Database internal mechanisms:
  • Tuning database configuration parameters.
  • Regular maintenance procedures (e.g., VACUUM for PostgreSQL).
• Archiving and cleanup:
  • Moving rarely used or outdated data to archive storage or deleting it.

As a Frontend developer, I can actively participate in query optimization, implementing frontend caching, and analyzing data received from the backend to identify anomalies. Close collaboration with the backend team is also essential for coordinated actions.

Example of frontend caching using React Query:

// Using useQuery for data fetching with caching
import { useQuery } from 'react-query';

const fetchUserData = async (userId) => {
  const response = await fetch(`/api/users/${userId}`);
  if (!response.ok) {
    throw new Error('Network response was not ok');
  }
  return response.json();
};

function UserProfile({ userId }) {
  const { data, error, isLoading } = useQuery(['user', userId], () => fetchUserData(userId));

  if (isLoading) return 'Loading...';
  if (error) return 'An error has occurred: ' + error.message;

  return (
    <div>
      <h2>{data.name}</h2>
      <p>{data.email}</p>
    </div>
  );
}