Prediction: Commutative DB Patterns Ahead
We will see a lot of commutative operators in eventually consistent datastores a year from now. It makes a lot of sense: we can then have some atomicity and still have the nice properties of eventual consistency.
Some example operators:
- increment(field, by_n)
- addToSet(field, value)
An example. The final result is the same regardless of the order of operations:
// x starts as { }
x.increment('a', 1);
x.increment('a', 3);
x.addToSet('b', 'foo');
x.addToSet('b', 'bar');
result: { a : 4, b : {bar,foo} }
