MongoDB：文档何时更新

Question

我知道我可以从objectid中提取文档的创建日期。

请参阅：When was a document added to a MongoDB collection

我想知道是否有类似的方式来知道文档何时更新？

好的，收到评论后，我用这个问题来创建我的changestream： How to set MongoDB Change Stream 'OperationType' in the C# driver?

我的代码如下：

IMongoCollection<RootRecord> collection = db.GetCollection<RootRecord>("companies");            
//Get the whole document instead of just the changed portion
ChangeStreamOptions options = new ChangeStreamOptions() { FullDocument = ChangeStreamFullDocumentOption.UpdateLookup };

//The operationType can be one of the following: insert, update, replace, delete, invalidate
var pipeline = new EmptyPipelineDefinition<ChangeStreamDocument<RootRecord>>().Match("{ operationType: { $in: [ 'replace', 'insert', 'update' ] } }");

var changeStream = collection.Watch(pipeline, options).ToEnumerable().GetEnumerator();
changeStream.MoveNext();    //Blocks until a document is replaced, inserted or updated in the TestCollection
ChangeStreamDocument<RootRecord> next = changeStream.Current;
changeStream.Dispose();

但这现在导致以下异常：

  

命令聚合失败：异常：无法识别的管道阶段名称：   “ $ changeStream”。

我需要做什么来解决此异常？