When is pool query used?

Recently I've started learning node and PostgresSQL. I've started reading documentation on node-pg, and I understood what is a pool and client. But usually a client would start a query, when would the pool's query method be used?

What is the proper way to add article images to database?

The rich text editor I am currently using is Quill.js. It provides a simple way to retrieve html content, and my question is how to retrieve the image to upload within the html to store in database?

Is it normal that when page refreshes, redux state is gone?

How does django-webpack-loader work with React's create-react-app?