5.4.4.3. Lazy Loading

Lazy loading (loading on demand) enables delayed loading of linked entities, i.e. they get loaded when their properties are accessed for the first time.

Lazy loading generates more database queries than eager fetching, but it is stretched in time.

  • For example, in case of lazy loading of a list of N instances of entity A, each containing a link to an instance of entity B, will require N+1 requests to DB.

  • In most cases, minimizing the number of requests to the database results in less response time and database load. The platform uses the mechanism of views to achieve this. Using view allows ORM to create only one request to the database with table joining for the above mentioned case.

Lazy loading works only for instances in Managed state, i.e. within the transaction which loaded the instance.