elasticsearch - 在ElasticSearch 6中使用过滤器按嵌套对象聚合

Question

我有一组文档代表ElasticSearsh 6中的属性单位。每个属性都有嵌套的每周费率数组:

{
   "name" : "Completely Awesome Cabin"
   "rates" : [
      {
         "start": "2018-06-09T00:00:00",
         "end": "2018-06-16T00:00:00",
         "weeklyRate": 100.0,
      },
      {
         "start": "2018-06-16T00:00:00",
         "end": "2018-06-23T00:00:00",
         "weeklyRate": 200.0,
      }
      ...
   ]    
   ...
}

我正在通过几个选项(包括日期)进行一些过滤。我需要添加聚合，以便在通过过滤器的所有单位之间为我提供最小和最大每周费用。我想这应该是带有过滤器的嵌套聚合。我怎样才能做到这一点？

Answer 1

这是在NEST 6.1.0上运行的完整示例

private static void Main()
{
    var index = "default";
    var pool = new SingleNodeConnectionPool(new Uri("http://localhost:9200"));
    var connectionSettings = new ConnectionSettings(pool)
        .DefaultIndex(index);

    var client = new ElasticClient(connectionSettings);

    if (client.IndexExists(index).Exists)
        client.DeleteIndex(index);

    client.CreateIndex(index, c => c
        .Mappings(m => m
            .Map<MyDocument>(mm => mm
                .AutoMap()
                .Properties(p => p
                    .Nested<Rate>(n => n
                        .AutoMap()
                        .Name(nn => nn.Rates)
                    )
                )
            )
        )
    );

    client.Bulk(b => b
        .IndexMany(new[] {
            new MyDocument
            {
                Name = "doc 1",
                Rates = new []
                {
                    new Rate
                    {
                        Start = new DateTime(2018, 6, 9),
                        End = new DateTime(2018, 6, 16),
                        WeeklyRate = 100
                    },
                    new Rate
                    {
                        Start = new DateTime(2018, 6, 16),
                        End = new DateTime(2018, 6, 23),
                        WeeklyRate = 200
                    }
                }
            },
            new MyDocument
            {
                Name = "doc 2",
                Rates = new []
                {
                    new Rate
                    {
                        Start = new DateTime(2018, 6, 9),
                        End = new DateTime(2018, 6, 16),
                        WeeklyRate = 120
                    },
                    new Rate
                    {
                        Start = new DateTime(2018, 6, 16),
                        End = new DateTime(2018, 6, 23),
                        WeeklyRate = 250
                    }
                }
            }
        })
        .Refresh(Refresh.WaitFor)
    );

    var searchResponse = client.Search<MyDocument>(s => s
        // apply your filtering in .Query(...) e.g. applicable date range
        .Query(q => q.MatchAll())
        // don't return documents, just calculate aggregations
        .Size(0)
        .Aggregations(a => a
            .Nested("nested_start_dates", n => n
                .Path(f => f.Rates)
                .Aggregations(aa => aa
                    .DateHistogram("start_dates", dh => dh
                        .Field(f => f.Rates.First().Start)
                        .Interval(DateInterval.Day)
                        .MinimumDocumentCount(1)
                        .Aggregations(aaa => aaa
                            .Min("min_rate", m => m
                                .Field(f => f.Rates.First().WeeklyRate)
                            )
                            .Max("max_rate", m => m
                                .Field(f => f.Rates.First().WeeklyRate)
                            )
                        )
                    )
                )
            )
        )
    );

    var nested = searchResponse.Aggregations.Nested("nested_start_dates");

    var startBuckets = nested.DateHistogram("start_dates").Buckets;

    foreach(var start in startBuckets)
    {
        var min = start.Min("min_rate").Value;
        var max = start.Max("max_rate").Value;

        Console.WriteLine($"{start.KeyAsString} - min: {min}, max: {max}");
    }
}

public class MyDocument
{
    public string Name {get;set;}

    public IEnumerable<Rate> Rates {get;set;}
}

public class Rate
{
    public DateTime Start {get;set;}

    public DateTime End {get;set;}

    public double WeeklyRate {get;set;}
}

将以下内容打印到控制台

2018-06-09T00:00:00.000Z - min: 100, max: 120
2018-06-16T00:00:00.000Z - min: 200, max: 250

您可能还对其他指标聚合(例如 Stats Agggregation)感兴趣