So I understand that MongoDB (and by proxy Mongoose) does not support transactions, but that operations involving a single document are always atomic. In looking over the Mongoose docs, I ran into Model.create which allows one to pass an array of documents and store them in a single action, like so:
var array = [{ type: 'jelly bean' }, { type: 'snickers' }];
Candy.create(array, function (err, jellybean, snickers) {
// ...
}
Is this action atomic? Does Mongo save all the documents at once, or does the Mongoose ODM loop through the array, saving one document at a time? Sources (or source code) would be greatly appreciated. (Also, I'm new, so please, don't shoot!)
MongoDB Wire Protocol accepts either single document or multiple documents with OP_INSERT. However, on the server they are still inserted one at a time.
In other words, if the server were to crash part-way through the insert, some documents would be inserted and others would not be. Within each document you are guaranteed consistent view of it - either it's all inserted or it's not. But for multiple documents no such guarantee exists.