This is the simple “create table” example isn’t? This table can hold millions of data (record) no doubt on that. But can you give me a guarantee on the performance – when I request some portion of data for a range of field ‘id’? You might say why don’t you add an “index” to the fields. Yes, exactly that will improve the performance of this table, it does increase, and by optimizing this field by assigning the ‘id‘ field an unsigned it doubles the speed of returning (with or without index and performance depends on the number of records you fetch) the results of a select query.