Scan and Scroll Substitute in ElasticSearch version 2.x (NEST C#)

Question

Ive successfully used Elastic 1.x scan and scroll with NEST API to get all documents matching my query. Started a new project and thought Ill use newest Elastic version 2.x, and stumbled on the first hurdle - how do I return all documents matching query (in c# using NEST)?

Any suggestions are appreciated, Thanks

Answer 1

Scroll is in Elasticsearch 2.x

synchronous version

var response = client.Search<object>(s => s
    // specify a scroll time of 2 minutes using string,
    // implicitly converts to Time type
    .Scroll("2m")
    .Sort(ss => ss
        // sorting on "_doc"
        .Ascending(SortSpecialField.DocumentIndexOrder)
    )
);

asynchronous version

var response = await client.SearchAsync<object>(s => s
    // specify a scroll time of 2 minutes using Time type
    .Scroll(new Time(2, Nest.TimeUnit.Minute))
    .Sort(ss => ss
         // sorting on "_doc"
        .Ascending(SortSpecialField.DocumentIndexOrder)
    )
);

More information on the Time units

Answer 2

I am not a NEST user, but the way that scan and scroll queries are done has changed in ES 2.X. Now, you can do scan and scroll using a simple sort query based on _doc. Please refer to: https://www.elastic.co/guide/en/elasticsearch/reference/current/search-request-scroll.html

curl -XGET 'localhost:9200/_search?scroll=1m' -d '
{
  "sort": [
    "_doc"
  ]
}
'

I hope I am helpful.