What is the best way to use a database for a large project?

Question

PHP

Hello!
I am creating a large project that will have a large load on the server.
There will be personal user accounts that will be loaded to the maximum. And here the question arises:
Use 1 database for all users - will it sooner or later result in a bunch of problems?
Or when registering a user, create your own database for him? If yes, what is the best way to do it?
And yet, which DBMS is better to use in my case? MySQL, PostgreSQL, MariaDB, MSSQL... ?

Answer 1

any sane database has mechanisms for scaling. So to each user on a DB is search.
As for "which one to use" - there is no single answer to this question. Choose the one you are more familiar with. Given PDO, migrating to another database is relatively easy.
and what is "my case" and "large load"? in absolute numbers?