The lazy loading in SQLAlchemy provides the developer with an option to use the select or joined modes, in which the lazy loading can be performed. When the developer goes with the select mode of loading the data, the loading of the datasets happens through the emission of SQL SELECT statements, which load the data on a per-requirement basis.

When using joined, the related datasets are loaded all at once through the emission of SQL JOIN statements. This technique is also known as joined eager loading.