[Sirupsen]

Ideally, I would add three graphs to the post:

(1) Table size on the x-axis, and time on the y-axis for index merge vs composite index

(2) Number of columns on the x-axis, and time on the y-axis for both

(3) Number of final matches on the x-axis, and time on the y-axis for both

But ran out of time and decided to test with the table size of 10M rows, and a 100-ish result set. That's in my experience a decent representation for what you might be doing with a relational database.