How does it work and what kind of burden does it carry?

Question

PHP

Hello.
Bulletin boards have the ability to select a region and, depending on the choice, different publications are displayed without changes in the url. The user's choice is stored in cookies.
1. How does this affect the database load and does it depend on cms?
2. Is caching possible?

Answer 1

1. Depends on the specific implementation of the site structure. From a city cookie, for example, only a selection of news can change, or the site template can switch completely to a completely different one.
2. Why not.

Answer 2

1) Too abstract question. If the database is designed correctly, there are keys, links, then everything will work quickly. A lot depends on the server configuration here. If you have 1,000 cities in the database and 1,000,000 ads, then this is not a load at all, especially on the same site with ads starting with the letter A, the links are one to one, i.e. one ad belongs to one city and you don’t need will make a pivot table for this, just add the location_id field to the ad and make a selection based on it.
2) There are many types of caching. What exactly did you decide to cache? Representation? Requests? In any case, it is possible, but you need to enter it when you already know the bottlenecks in the system.