Use map vs array of embedded documents?

[Takis]

Hello

When you send 1 query,you can change many things in the document and change will be
atomic.MongoDB offers pipeline updates also,that can do all sorts of complicated updates
in 1 document.(you can send multiple queries also,but you need transactions to make them atomic)

For an example of how to update an array with members documents see this query

Perform multiple updates (upserts) on Embedded documents

Hello : ) The above query was not just a array update,it was to change the data the way you said you want them.In the last query you sended you use $push operator,inside an aggregation and you cant do that.You cant mix aggregation operators/query operators/update operators. Exception is that you can use aggregate operators to query with $expr. You can do array update.The bellow does filter to check if friend already existed based on frined._id(if filter result is empty=> its new friend) i…

Its atomic and its fast.It checks if new member => update,else add in the end of the array.
In your case if you already know if new or existing comment,you can make it even faster,
and avoid the check.