Explain API

原文链接 : https://www.elastic.co/guide/en/elasticsearch/reference/current/search-explain.html

译文链接 : http://apache.wiki/display/Elasticsearch/Explain+API

贡献者 : @琴剑蓝天

Explain API 计算查询和特定文档的分数说明。 这可以提供有用的反馈，无论文档是否匹配特定查询。

index 和 type 参数分别期望单个索引和单个类型。

用法

完整查询示例：

GET /twitter/tweet/0/_explain
{
      "query" : {
        "match" : { "message" : "elasticsearch" }
      }
}

这将产生以下结果：

{
  "_index" : "twitter",
  "_type" : "tweet",
  "_id" : "0",
  "matched" : true,
  "explanation" : {
    "value" : 1.55077,
    "description" : "sum of:",
    "details" : [ {
      "value" : 1.55077,
      "description" : "weight(message:elasticsearch in 0) [PerFieldSimilarity], result of:",
      "details" : [ {
        "value" : 1.55077,
        "description" : "score(doc=0,freq=1.0 = termFreq=1.0\n), product of:",
        "details" : [ {
          "value" : 1.3862944,
          "description" : "idf(docFreq=1, docCount=5)",
          "details" : [ ]
        }, {
          "value" : 1.1186441,
          "description" : "tfNorm, computed from:",
          "details" : [
            { "value" : 1.0, "description" : "termFreq=1.0", "details" : [ ] },
            { "value" : 1.2, "description" : "parameter k1", "details" : [ ] },
            { "value" : 0.75, "description" : "parameter b", "details" : [ ] },
            { "value" : 5.4, "description" : "avgFieldLength", "details" : [ ] },
            { "value" : 4.0, "description" : "fieldLength", "details" : [ ] }
          ]
        } ]
      } ]
    }, {
      "value" : 0.0,
      "description" : "match on required clause, product of:",
      "details" : [ {
        "value" : 0.0,
        "description" : "# clause",
        "details" : [ ]
      }, {
        "value" : 1.0,
        "description" : "_type:tweet, product of:",
        "details" : [
          { "value" : 1.0, "description" : "boost", "details" : [ ] },
          { "value" : 1.0, "description" : "queryNorm", "details" : [ ] }
        ]
      } ]
    } ]
  }
}

还有一种更简单的通过 q 参数指定查询的方法。 然后解析指定的 q 参数值，就像使用 query_string 查询一样。 在api中的 q 参数的用法示例：

GET /twitter/tweet/0/_explain?q=message:search

这将产生与先前请求相同的结果。

所有的参数