Explain the principle of greedy data loading in systems and why it is used.

Eager loading is a strategy of loading related data immediately when querying the main entity.

For example, if you have an "Order" object and related "Products", eager loading will load all products together with the order in a single query.

This is used to reduce the number of database queries and prevent the "N+1 query" problem, where a separate query is executed for each related entity.

Example in C# using Entity Framework:

var orders = context.Orders.Include(o => o.Products).ToList();

Here, Include indicates eager loading of related products along with the orders.