What actions will you take if the delays in database query execution become significant under increased system load?

If the system load increases and query response times to the database become significant, the following steps should be taken:

1. Profiling and query analysis: Use monitoring and logging tools to identify slow queries and bottlenecks.

2. Query optimization: Rewrite or optimize SQL queries, add necessary indexes, and remove redundant operations.

3. Caching: Implement caching for frequently requested data (e.g., using Redis or Memcached) to reduce database load.

4. Database scaling: Consider vertical scaling (increasing server resources) or horizontal scaling (replication, sharding).

5. Connection pool: Configure a connection pool for efficient connection management.

6. Asynchronous processing: Move heavy operations to background tasks to avoid blocking main queries.

7. Architectural changes: Use CQRS, event sourcing, or read/write separation if necessary.

Example of index setup in PostgreSQL:

CREATE INDEX idx_users_email ON users(email);

This will help speed up searches by the email field if queries often filter by it.