We can use the BulkWrite API for batch operations. In our previous insert many documents example, this would be:

@collection.bulk_write([ { insertMany: documents
                     }],
                   ordered: true)

The BulkWrite API can take the following parameters:

• insertOne
• updateOne
• updateMany
• replaceOne
• deleteOne
• deleteMany

One version of these commands will insert/update/replace/delete a single document even if the filter that we specify matches more than one document. In this case, it's important to have a filter that matches a single document to avoid unexpected behaviors.

It's also possible, and a perfectly valid use case, to include several operations in the first argument of the bulk_write command. This allows us to issue commands in a sequence when we have operations that depend on each other and we want to batch them in a logical order according to our business logic. Any error will stop ordered:true batch writes and we will need to manually roll back our operations. A notable exception is writeConcern errors, for example requesting a majority of our replica set members to acknowledge our write. In this case, batch writes will go through and we can observe the errors in the writeConcernErrors result field.

old_book = @collection.findOne(name: 'MongoDB for experts')
new_book = { isbn: 201, name: 'MongoDB for experts, 2nd Edition', price: 55 }
@collection.bulk_write([ {deleteOne: old_book}, { insertOne: new_book
                     }],
                   ordered: true)

In the previous example, we made sure that we deleted the original book before adding the new (and more expensive) edition of our MongoDB for experts book.

BulkWrite can batch up to 1,000 operations. If we have more than 1,000 underlying operations in our commands, these will be split into chunks of thousands. It is a good practice to try to keep our write operations to a single batch if we can, to avoid unexpected behavior.