Difference Between updateOne and replaceOne?

So the basic explanation is that updateOne updates fields of an existing document whereas replaceOne replaces the whole document.
But my question lies in the case where $set is not used in updateOne.
This makes updateOne exactly same as replaceOne , atleast at first look.
Please let me know if there is some differences like indexing, or value of _id changes,etc, with respect to the above two methods.

Take a look at https://docs.mongodb.com/manual/reference/method/db.collection.updateOne/ and https://docs.mongodb.com/manual/reference/operator/update/. You will see that $set is only a subset of what updateOne can do. In addition look at the upsert parameter.

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Hi @Koushik_10617,

In addition to @steevej-1495,

Starting in MongoDB 4.2, the updateOne() function can also have an aggregation pipeline consisting of these possible stages:

Please refer our documentation for more information on this.

Hope it helps. If you have any other query, please feel free to get back to us.

Happy Learning :slight_smile:

Thanks,
Shubham Rajan
Curriculum Support Engineer

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