is having millions of tables and millions of rows within them a common practice in MySQL database design?

Question

I am doing database design for an upcoming web app, and I was wondering from anybody profusely using mysql in their current web apps if this sort of design is efficient for

Answer 1

In addition to what others have said, don't forget that finding the right table based on the given table name also takes time. How much time? Well, this is internal to DBMS and likely not documented, but probably more than you think.

So, a query searching for a row can either take:

1. Time to find the table + time to find the row in a (relatively) small table.
2. Or, just the time to find a row in one large table.

The (2) is likely to be faster.

Also, frequently using different table names in your queries makes query preparation less effective.