如何根据来源匹配在Elasticsearch中获得准确的总和? [英] How do i get accurate sum in elasticsearch based on source hits?

问题描述

如何在Elasticsearch中获得确切的总和?前言，我目前正在使用Elasticsearch 5.6，我的索引映射如下所示:

How do i get an exact sum aggregation in elasticsearch? Fore reference i am currently using elasticsearch 5.6 and the my index mapping looks like this:

{
  "my-index":{
    "mappings":{
      "my-type":{
        "properties":{
          "id":{
            "type":"keyword"
          },
          "fieldA":{
            "type":"double"
          },
          "fieldB":{
            "type":"double"
          },
          "fieldC":{
            "type":"double"
          },
          "version":{
            "type":"long"
          }
        }
      }
    }
  }
}

(使用Java客户端)生成的搜索查询为:

The search query generated (using java client) is:

{
 /// ... some filters here
 "aggregations" : {
       "fieldA" : {
         "sum" : {
           "field" : "fieldA"
         }
       },
       "fieldB" : {
         "sum" : {
           "field" : "fieldB"
         }
       },
       "fieldC" : {
         "sum" : {
           "field" : "fieldC"
         }
       }
     }
}

但是我的结果点击产生以下内容:

However my result hits generate the following:

{
    "took": 10,
    "timed_out": false,
    "_shards": {
        "total": 3,
        "successful": 3,
        "skipped": 0,
        "failed": 0
    },
    "hits": {
        "total": 5,
        "max_score": 3.8466966,
        "hits": [
            {
                "_index": "my-index",
                "_type": "my-type",
                "_id": "25a203b63e264fd2be13db006684b06d",
                "_score": 3.8466966,
                "_source": {
                    "fieldC": 108,
                    "fieldA": 108,
                    "fieldB": 0
                }
            },
            {
                "_index": "my-index",
                "_type": "my-type",
                "_id": "25a203b63e264fd2be13db006684b06d",
                "_score": 3.8466966,
                "_source": {
                    "fieldC": -36,
                    "fieldA": 108,
                    "fieldB": 144
                }
            },
            {
                "_index": "my-index",
                "_type": "my-type",
                "_id": "25a203b63e264fd2be13db006684b06d",
                "_score": 3.8466966,
                "_source": {
                    "fieldC": -7.2,
                    "fieldA": 1.8,
                    "fieldB": 9
                }
            },
            {
                "_index": "my-index",
                "_type": "my-type",
                "_id": "25a203b63e264fd2be13db006684b06d",
                "_score": 3.8466966,
                "_source": {
                    "fieldC": 14.85,
                    "fieldA": 18.9,
                    "fieldB": 4.05
                }
            },
            {
                "_index": "my-index",
                "_type": "my-type",
                "_id": "25a203b63e264fd2be13db006684b06d",
                "_score": 3.8466966,
                "_source": {
                    "fieldC": 36,
                    "fieldA": 36,
                    "fieldB": 0
                }
            }
        ]
    },
    "aggregations": {
        "fieldA": {
            "value": 272.70000000000005
        },
        "fieldB": {
            "value": 157.05
        },
        "fieldC": {
            "value": 115.64999999999999
        }
    }
}

我为什么得到:

115.64999999999999，而不是fieldC中的115.65272.70000000000005，而不是fieldA中的272.7

115.64999999999999 instead of 115.65 in fieldC 272.70000000000005 instead of 272.7 in fieldA

我应该使用float而不是double吗?还是有一种方法可以更改查询而无需使用无痛脚本并且使用具有指定精度和舍入模式的Java BigDecimal?

should i use float instead of double? or is there a way i can change the query without using painless script and using java's BigDecimal with specified precision and rounding mode?

推荐答案

这与JavaScript中的浮点数精度有关(类似于).

It has to do with float number precision in JavaScript (similar to what can be seen here and explained here).

有两种检查方法:

A.如果安装了node.js，只需在提示符下键入 node ，然后输入所有fieldA值的总和:

A. If you node.js installed, just type node at the prompt and then enter the sum of all fieldA values:

 $ node
 108 - 36 - 7.2 + 14.85 + 36
 115.64999999999999            <--- this is the answer

B.打开浏览器的开发人员工具，然后选择控制台"视图.然后输入与上述相同的总和:

B. Open the Developer tools of your browser and pick the Console view. Then type the same sum as above:

 > 108-36-7.2+14.85+36
 < 115.64999999999999

如您所见，两个结果都与您在ES响应中看到的一致.

As you can see, both results are consistent with what you're seeing in your ES response.

一种避免这种情况的方法是将数字存储为普通整数(即1485代替14.85，3600代替36等)或

One way to circumvent this is to store your numbers either as normal integers (i.e. 1485 instead of 14.85, 3600 instead of 36, etc) or as scaled_float with a scaling factor of 100 (or bigger depending on the precision you need)

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