However, if there is enough spare capacity, and if contention between transactions is not too high, optimistic concurrency control techniques tend to perform better than pessimistic ones. Contention can be reduced with commutative atomic operations: for example, if several transactions concurrently want to increment a counter, it doesn’t matter in which order the increments are applied (as long as the counter isn’t read in the same transaction), so the concurrent increments can all be applied without conflicting.
