mongodb - What is the difference between save and insert in Mongo DB?

Question

What is the difference between save and insert in Mongo DB? both looks the same

db.users.save({username:"google",password:"google123"})

db.users.insert({username:"google",password:"google123"})

Answer 1

Save Vs Insert :

In your given examples, the behavior is essentially the same.

save behaves differently if it is passed with an "_id" parameter.

For save, If the document contains _id, it will upsert querying the collection on the _id field, If not, it will insert.

If a document does not exist with the specified _id value, the save() method performs an insert with the specified fields in the document.

If a document exists with the specified _id value, the save() method performs an update, replacing all field in the existing record with the fields from the document.

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Save vs Update :

update modifies an existing document matched with your query params. If there is no such matching document, that's when upsert comes in picture.

• upsert : false : Nothing happens when no such document exist
• upsert : true : New doc gets created with contents equal to query params and update params

save : Doesn't allow any query-params. if _id exists and there is a matching doc with the same _id, it replaces it. When no _id specified/no matching document, it inserts the document as a new one.