Atomicty of the entire operation

[revit]

I ran the following scenario:

First, inserted documents:
for (var i = 0; i <100; i++) {db.col1.insert({_id: i, "new5" :22})}

Then updated them with the following command:
db.col1.updateMany({}, {$set: {  "new5": 900, "new6" : 600  }  })

The server was killed while the updateMany command was running and after it was up again I checked the status of the collection.
I saw that some of documents were with the updated value "new5" : 900, "new6" : 600 and other remained with the original value although I expected a rollback will be applied and all the documents
will be retrieved to the old value. Am I missing something? is there a special mode which guarantees the atomicty of the entire update operation? Thanks!

[John Murphy]

Hi revit,

In MongoDB, a write operation is atomic on the level of a single document. Operations that involve multiple documents are not atomic.

For cases where a sequence of write operations must operate as if in a single transaction, you can follow our manual on how to perform a two-phase commit in your application.

Regards,
John Murphy

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