Re: [mongodb-user] Batch Save to MongoDB C# Driver

[Robert Stam]

You have to save the documents one at a time:

    foreach (var document in autolookuplist)

    {

        idcollection.Save(document);

    }

Why don't you just save them one at a time in the loop (using your commented out call to Save)?

On Tue, May 21, 2013 at 9:00 AM, mark gamache <gamach...@gmail.com> wrote:

I've asked this on StackOverflow but I think this might be a better place:

I am having difficulty batch saving MongoDB documents using the C# driver. Here's sample code that inserts a Document with a GUID BsonID. Saving one at a time works. If I insert the documents into a list and use the save command it fails with an "Save can only be used with documents that have an Id."error. I think it might be a bug in the driver not recognizing the custom ID field, bu I am not sure. Any thoughts?

var autolookuplist = new List<BsonDocument>();
            Parallel.ForEach(docs, webdoc =>
                {
                    lock (autolookuplist)
                    {
                        autoID++;
                        var hold = new APAUtoIDGuidLookup() {AutoIncrementID = autoID, ID = webdoc.ID};
                      autolookuplist.Add(hold.ToBsonDocument());
                    }

                  //this works
                 //   idcollection.Save(new APAUtoIDGuidLookup() { AutoIncrementID = autoID, ID = webdoc.ID });
                });


          //this doesn't work
          idcollection.Save(autolookuplist);

here's the document class

public class  APAUtoIDGuidLookup
{
    [BsonId]
    public Guid ID { get; set; }
    public int AutoIncrementID { get; set; }
}

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[mark gamache]

Thanks, I may have to save one at a time, but it's about performance.This server will be under considerable load and if I have 1000 (or more) documents to update I would prefer that it be 1 network/DIsk IO access instead of 1000.

This is a bug/oversight in the C# driver. It looks like MongoDB supports batch updates, it's just the C# driver doesn't.   

[Bernie Hackett]

> This is a bug/oversight in the C# driver. It looks like MongoDB supports batch updates, it's just the C# driver doesn't.

No, it doesn't. https://jira.mongodb.org/browse/SERVER-2172

[Robert Stam]

The current version of the server only supports batch inserts, it does not support batch updates. There are plans to support batch updates in the future.

Save is based on top of Update because it works with either new documents or existing documents.

If you know that all your documents are new (like they are in your case), you could use InsertBatch instead.

[mark gamache]

I guess it doesn't thanks for the heads up. That's disappointing news and it looks like that jira ticket is old, so it's probably not going to happen soon. Once the system is in production 90% of the calls will be updates and not inserts so I'll have to stick with one-at-a-time.