# Scroll API(C# NEST) fails

**URL:** <https://discuss.elastic.co/t/scroll-api-c-nest-fails/129320>\
**Category:** Elasticsearch\
**Created:** [April 24, 2018, 2:11pm UTC](https://discuss.elastic.co/t/scroll-api-c-nest-fails/129320 "2018-04-24T14:11:49Z")\
**Posts on this page:** 1\
**Showing post:** 2

<div class="post-metadata">

**Author:** ![forloop](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/forloop/32/9021_2.png) [@forloop](https://discuss.elastic.co/u/forloop)\
**Post date:** [May 1, 2018, 6:47am UTC](https://discuss.elastic.co/t/scroll-api-c-nest-fails/129320/2 "2018-05-01T06:47:25Z")

</div>

I've formatted your code this time; please use the `</>` button to format your code in future, or surround in ``` (triple backticks) with optional language after the first block. Trying to read unformatted code makes it much harder to help 🙂

Have you seen the `ScrollAll()` helper method? I think this would fit well with your use case:

```auto
var index = "my_index_name";
var numberOfShards = 3;
var seenDocuments = 0;
var documents = new ConcurrentBag<IReadOnlyCollection<MyDocument>>();

client.ScrollAll<MyDocument>("1m", numberOfShards, s => s
    .MaxDegreeOfParallelism(numberOfShards / 2)
    .Search(search => search
        .Index(index)
        .AllTypes()
        .MatchAll()
    )
).Wait(TimeSpan.FromMinutes(5), r =>
{
    documents.Add(r.SearchResponse.Documents);       
    Interlocked.Add(ref seenDocuments, r.SearchResponse.Hits.Count);
});

```

`ScrollAll()` can send concurrent scroll requests using slicing, and you can adjust the overall time to wait to fetch all documents with the `TimeSpan` passed to `.Wait()`. Using `ScrollAll()`, you can process documents as they are scrolled.

You can have more control with

```auto
var index = "my_index_name";
var numberOfShards = 3;
var seenDocuments = 0;
var documents = new ConcurrentBag<IReadOnlyCollection<MyDocument>>();

var observable = client.ScrollAll<MyDocument>("1m", numberOfShards, s => s
    .MaxDegreeOfParallelism(numberOfShards / 2)
    .Search(search => search
        .Index(index)
        .AllTypes()
        .MatchAll()
    )
);

var waitHandle = new ManualResetEvent(false);
Exception exception = null;
observable.Subscribe(new ScrollAllObserver<MyDocument>(
    onNext: r =>
    {
        documents.Add(r.SearchResponse.Documents);
        Interlocked.Add(ref seenDocuments, r.SearchResponse.Hits.Count);
    },
    onError: e => 
    { 
        exception = e;
        waitHandle.Set();
    },
    onCompleted: () => waitHandle.Set()
));

waitHandle.WaitOne();

if (exception != null)
    throw exception;

```

---

_[View the full topic](https://discuss.elastic.co/t/scroll-api-c-nest-fails/129320)._