Does having many databases affect MySQL performance?

In MySQL, does altering a table's AUTO_INCREMENT value to start at a really high value affect read/write performance?

• This is compared to a scenario of a table which has the same number of rows (O(10MM)) but has AUTO_INCREMENT that started at 0 (vs. something O(100MM)).

• Answer:

  I really doubt it: integers are fixed-sized, so either way the computer has to deal with the same number of bits during integer comparisons or disk IO. The only issue I can see is if the higher start value meant you had to use BIGINT instead of INT, but that's not the case here. I'm assuming that you're inserting data into initially empty tables, since otherwise you might see performance changes due to the alter command rebuilding your index/table. Disclaimer: I don't know much about how computers or MySQL work on a low level and I probably shouldn't be answering this question.