The ability to guarantee that a batch of writes occurs together.
One reviewer wanted to change that to occur.
I'm not sure if this is my idiom (Australian of U.K. origin) vs American or if I'm wrong.
I regarded batch of writes as a singular collective noun.
This English Club reference and others suggest using a plural verb with collective noun is less common in American English.
edit To clarify, the sentence is in a book about programming computer databases and the full sentence is much longer, possibly too long!
Those three operations are all we need; everything else is sugar on top (or maybe something a bit more nutritious, like the ability to guarantee that a batch of writes occurs together).