Using flat catalog will speedup your website to a certain extent as Magento does not need to join multiple tables to pull products details. When you use the flat catalog system, all the EAV attributes will copied to flat table on the fly.
This tutorial we are showing how to enable flat catalog in Magento2.
- In the Admin Panel, from left menu
Stores -> Settings -> Configurations.
- In the resulting window , Select
Catalogfrom the left menu and open the option
- Choose Yes in the Use Flat Catalog Category field.
- Choose Yes in the Use Flat Catalog Product field.