@gaurav_harsh1 wrote:
3). Follow this Store > Configuration > Catalog.
Then click on Catalog which is under the Catalog tab. In here, you will see the Storefront section.
When you have seen it, find two fields which are Use Flat Catalog Category and Use Flat Catalog Product, and change these fields to Yes.
4). Go to Store > Configuration > Advanced.
Under the Advanced tab, click Developer. In the Javascript Settings section, change the values in three fields Merge JavaScript Files, Enable JavaScript Bundling and Minify JavaScript Files to Yes. Then, change the fields Merge CSS Files and Minify CSS Files in the CSS Settings tab to Yes.
Just to point out that Magento no longer recommends the use of a flat catalog as a best practice as of version 2.1.x and above.
You can read more about it here:-
https://support.magento.com/hc/en-us/articles/360034631192
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