You have different collections in MongoDb with de-normalized attributes. As you may know, due to its not-join nature, MongoDb tends to encourage repetition of the same value in different collections (de-normalization). In this MongoDb is opposed to a more SQL-like approach where you usually reference only the ID of the value with a foreign key.
If you are coming over from Yii 1.x to Yii 2, and already read this guide, you may note that namespaces are very important in Yii 2 to identify classes. But do you know the list of seeded path aliases that come shipped with a basic or advanced app? Here is my attempt to list them.
Ok, you have installed a Yii 2 basic or advanced app for the first time and completed the post install steps. You have picked up a few extensions to install for the first time as well. You would already see a composer.lock file in your application root folder.
The tips here are for advanced usages of composer and its assumed you have read about using composer and have a knowledge of your vendor packages to be updated. Let's consider, you want to update only one specific yii2 vendor library, without updating all the other extension packages?