Add missing execution hint options to terms aggregation

Closes #1180

Author: gmarz

src/Nest/Enums/TermsAggregationExecutionHint.cs

@@ -1,6 +1,7 @@
 using System.Runtime.Serialization;
 using Newtonsoft.Json;
 using Newtonsoft.Json.Converters;
+using System;
 
 namespace Nest
 {
@@ -18,7 +19,23 @@ public enum TermsAggregationExecutionHint
 		/// <summary>
 		/// Order by using ordinals of the field values instead of the values themselves
 		/// </summary>
+		[Obsolete("ordinals was removed from ES in version 1.3.  Use global_ordinals instead.")]
 		[EnumMember(Value = "ordinals")]
-		Ordinals
+		Ordinals,
+		/// <summary>
+		/// Order by using ordinals of the field and preemptively allocating one bucket per ordinal value
+		/// </summary>
+		[EnumMember(Value = "global_ordinals")]
+		GlobalOrdinals,
+		/// <summary>
+		/// Order by using ordinals of the field and dynamically allocating one bucket per ordinal value
+		/// </summary>
+		[EnumMember(Value = "global_ordinals_hash")]
+		GlobalOrdinalsHash,
+		/// <summary>
+		/// Order by using per-segment ordinals to compute counts and remap these counts to global counts using global ordinals
+		/// </summary>
+		[EnumMember(Value = "global_ordinals_low_cardinality")]
+		GlobalOrdinalsLowCardinality
 	}
 }

src/Tests/Nest.Tests.Unit/ObjectInitializer/Search/SearchBody.json

@@ -70,7 +70,7 @@
       "terms": {
         "field": "name",
         "size": 10,
-        "execution_hint": "ordinals"
+        "execution_hint": "global_ordinals"
       },
       "aggs": {
         "max_count": {

src/Tests/Nest.Tests.Unit/ObjectInitializer/Search/SearchRequestTests.cs

@@ -121,7 +121,7 @@ public SearchRequestTests()
 						{
 							Field = Property.Path<ElasticsearchProject>(p=>p.Name),
 							Size = 10,
-							ExecutionHint = TermsAggregationExecutionHint.Ordinals,
+							ExecutionHint = TermsAggregationExecutionHint.GlobalOrdinals,
 						},
 						Aggregations = new Dictionary<string, IAggregationContainer>
 						{