Please have a look at http://docs.mongodb.org/manual/applications/update/ "The update() method can either replace the existing document with the new document* or update specific fields in the existing document.*" "Modifier Operators" such as $set, are performed in the context of the database and not at the client. See also here (german): http://books.google.de/books?id=6wAJLJRxFt8C&pg=PA156&lpg=PA156&dq=%22Modifi... In this book, the autor writes, that you will go to database hell, if you always update the whole document instead of single fields. :-) What are the experiences of bigger projects using MongoTalk - do you always write the *whole *collection? What about the performance with this solution? Is this feasible? It sounds strange to me. -- View this message in context: http://forum.world.st/does-MongoTalk-implement-modifier-operators-e-g-set-tp... Sent from the Pharo Smalltalk Users mailing list archive at Nabble.com.