MYSQL OR vs IN performance

Question

I am wondering if there is any difference in regards to performance between the following

SELECT ... FROM ... WHERE someFIELD IN(1,2,3,4)

SELECT ... FROM ..         


        

Answer 1

I know that, as long as you have an index on Field, the BETWEEN will use it to quickly find one end, then traverse to the other. This is most efficient.

Every EXPLAIN I've seen shows "IN ( ... )" and " ... OR ..." to be interchangeable and equally (in)efficient. Which you would expect, since the optimizer has no way to know whether or not they comprise an interval. It's also equivalent to a UNION ALL SELECT on the individual values.