Scroll example in ElasticSearch NEST API -

i using .from() , .size() methods retrieve documents elastic search results.

below sample example -

isearchresponse<dynamic> bresponse = objelasticclient.search<dynamic>(s => s.from(0).size(25000).index("accounts").alltypes().query(query)); 

recently came across scroll feature of elastic search. looks better approach from() , size() methods fetch large data.

https://www.elastic.co/guide/en/elasticsearch/reference/current/search-request-scroll.html

i looking example on scroll feature in nest api.

can please provide nest example?

thanks, sameer

internal implementation of nest reindex uses scroll move documents 1 index another.

it should starting point.

below can find interesting code github.

var page = 0; var searchresult = this.currentclient.search<t>(     s => s         .index(fromindex)         .alltypes()         .from(0)         .size(size)         .query(this._reindexdescriptor._queryselector ?? (q=>q.matchall()))         .searchtype(searchtype.scan)         .scroll(scroll)     ); if (searchresult.total <= 0)     throw new reindexexception(searchresult.connectionstatus, "index " + fromindex + " has no documents!"); ibulkresponse indexresult = null; {     var result = searchresult;     searchresult = this.currentclient.scroll<t>(s => s         .scroll(scroll)         .scrollid(result.scrollid)     );     if (searchresult.documents.hasany())         indexresult = this.indexsearchresults(searchresult, observer, toindex, page);     page++; } while (searchresult.isvalid && indexresult != null && indexresult.isvalid && searchresult.documents.hasany()); 

also can take @ integration test scroll

[test] public void searchtypescan() {     var scanresults = this.client.search<elasticsearchproject>(s => s         .from(0)         .size(1)         .matchall()         .fields(f => f.name)         .searchtype(searchtype.scan)         .scroll("2s")     );     assert.true(scanresults.isvalid);     assert.false(scanresults.fieldselections.any());     assert.isnotnullorempty(scanresults.scrollid);      var results = this.client.scroll<elasticsearchproject>(s=>s         .scroll("4s")          .scrollid(scanresults.scrollid)     );     var hitcount = results.hits.count();     while (results.fieldselections.any())     {         assert.true(results.isvalid);         assert.true(results.fieldselections.any());         assert.isnotnullorempty(results.scrollid);         var localresults = results;         results = this.client.scroll<elasticsearchproject>(s=>s             .scroll("4s")             .scrollid(localresults.scrollid));         hitcount += results.hits.count();     }     assert.areequal(scanresults.total, hitcount); }