MongoDB's Upsert

The three parameters of the MongoDB Update method are Upsert, which is a Boolean type and the default is False. When it is true, the Update method first finds the record that matches the first parameter, and when it is updated with the second parameter, inserts one if no record matching the first argument is found (Upsert's name is also interesting as a hybrid: Update+insert)

Look at the following example:

Db.post.update ({count:100},{"$inc": {count:10}},true);

When the count=100 record is not found, automatically inserts a count=100, then adds 10, and finally gets a count=110 record.

MongoDB's Upsert