MongoDB Java API：com.mongodb.DBCollection.Save（）和com.mongodb.DBCollection.Insert（）之间的区别？

Question

It looks these two methods both save a BasicDbObject to a collection instance.What is the difference between these two methods? com.mongodb.DBCollection.Insert() com.mongodb.DBCollection.Save()

Answer 1

Save can only save one object at a time. If _id is provided and it already exists, the new document will overwrite the previously existing one. If it doesn't exist, it will do an insert.

Insert can take a single object or an ArrayList of objects and do a "bulk insert" of them.

If you give an existing _id to an insert it will cause a duplicate Id exception.

Answer 2

.insert is only for insert, while .save can do insert or update.

com.mongodb.DBCollection.Save

Saves an object to this collection (does insert or update based on the object _id).

Answer 3

Save will either insert or update if the document has a set _id and insert will just insert.

You can read more about it here: http://www.mongodb.org/display/DOCS/Updating/#Updating- {{save%28%29}}inthemongoshell