过采样处理器

oversample 请求处理器将搜索请求的 size 参数乘以指定的 sample_factor（>= 1.0），并将原始值保存在 original_size 管道变量中。oversample 处理器设计用于与 truncate_hits 响应处理器 配合使用，但也可以单独使用。

请求体字段

下表列出了所有请求字段。

字段	数据类型	描述
sample_factor	浮点数	在处理搜索请求之前将应用于 size 参数的乘数因子（>= 1.0）。必需。
context_prefix	字符串	可用于限定 original_size 变量的作用域，以避免冲突。可选。
tag	字符串	处理器的标识符。可选。
description	字符串	处理器的描述。可选。
ignore_failure	布尔值	如果为 true，UDB-SX 忽略此处理器的任何故障 并继续运行搜索管道中的其余处理器。可选。默认值为 false。

示例

以下示例演示了使用包含 oversample 处理器的搜索管道。

设置

创建一个名为 my_index 的索引，包含许多文档：

POST /_bulk
{ "create":{"_index":"my_index","_id":1}}
{ "doc": { "title" : "document 1" }}
{ "create":{"_index":"my_index","_id":2}}
{ "doc": { "title" : "document 2" }}
{ "create":{"_index":"my_index","_id":3}}
{ "doc": { "title" : "document 3" }}
{ "create":{"_index":"my_index","_id":4}}
{ "doc": { "title" : "document 4" }}
{ "create":{"_index":"my_index","_id":5}}
{ "doc": { "title" : "document 5" }}
{ "create":{"_index":"my_index","_id":6}}
{ "doc": { "title" : "document 6" }}
{ "create":{"_index":"my_index","_id":7}}
{ "doc": { "title" : "document 7" }}
{ "create":{"_index":"my_index","_id":8}}
{ "doc": { "title" : "document 8" }}
{ "create":{"_index":"my_index","_id":9}}
{ "doc": { "title" : "document 9" }}
{ "create":{"_index":"my_index","_id":10}}
{ "doc": { "title" : "document 10" }}

创建搜索管道

以下请求创建一个名为 my_pipeline 的搜索管道，其中包含一个 oversample 请求处理器，该处理器请求比 size 中指定的命中数多 50%：

PUT /_search/pipeline/my_pipeline 
{
  "request_processors": [
    {
      "oversample" : {
        "tag" : "oversample_1",
        "description" : "This processor will multiply `size` by 1.5.",
        "sample_factor" : 1.5
      }
    }
  ]
}

使用搜索管道

在不使用搜索管道的情况下搜索 my_index 中的文档：

POST /my_index/_search
{
  "size": 5
}

响应包含五个命中项：

响应

{
  "took" : 3,
  "timed_out" : false,
  "_shards" : {
    "total" : 1,
    "successful" : 1,
    "skipped" : 0,
    "failed" : 0
  },
  "hits" : {
    "total" : {
      "value" : 10,
      "relation" : "eq"
    },
    "max_score" : 1.0,
    "hits" : [
      {
        "_index" : "my_index",
        "_id" : "1",
        "_score" : 1.0,
        "_source" : {
          "doc" : {
            "title" : "document 1"
          }
        }
      },
      {
        "_index" : "my_index",
        "_id" : "2",
        "_score" : 1.0,
        "_source" : {
          "doc" : {
            "title" : "document 2"
          }
        }
      },
      {
        "_index" : "my_index",
        "_id": "3",
        "_score" : 1.0,
        "_source" : {
          "doc" : {
            "title" : "document 3"
          }
        }
      },
      {
        "_index" : "my_index",
        "_id" : "4",
        "_score" : 1.0,
        "_source" : {
          "doc" : {
            "title" : "document 4"
          }
        }
      },
      {
        "_index" : "my_index",
        "_id" : "5",
        "_score" : 1.0,
        "_source" : {
          "doc" : {
            "title" : "document 5"
          }
        }
      }
    ]
  }
}

要使用管道进行搜索，请在 search_pipeline 查询参数中指定管道名称：

POST /my_index/_search?search_pipeline=my_pipeline
{
  "size": 5
}

响应包含 8 个文档（5 * 1.5 = 7.5，向上取整为 8）：

响应

{
  "took" : 13,
  "timed_out" : false,
  "_shards" : {
    "total" : 1,
    "successful" : 1,
    "skipped" : 0,
    "failed" : 0
  },
  "hits" : {
    "total" : {
      "value" : 10,
      "relation" : "eq"
    },
    "max_score" : 1.0,
    "hits" : [
      {
        "_index" : "my_index",
        "_id" : "1",
        "_score" : 1.0,
        "_source" : {
          "doc" : {
            "title" : "document 1"
          }
        }
      },
      {
        "_index" : "my_index",
        "_id" : "2",
        "_score" : 1.0,
        "_source" : {
          "doc" : {
            "title" : "document 2"
          }
        }
      },
      {
        "_index" : "my_index",
        "_id" : "3",
        "_score" : 1.0,
        "_source" : {
          "doc" : {
            "title" : "document 3"
          }
        }
      },
      {
        "_index" : "my_index",
        "_id" : "4",
        "_score" : 1.0,
        "_source" : {
          "doc" : {
            "title" : "document 4"
          }
        }
      },
      {
        "_index" : "my_index",
        "_id" : "5",
        "_score" : 1.0,
        "_source" : {
          "doc" : {
            "title" : "document 5"
          }
        }
      },
      {
        "_index" : "my_index",
        "_id" : "6",
        "_score" : 1.0,
        "_source" : {
          "doc" : {
            "title" : "document 6"
          }
        }
      },
      {
        "_index" : "my_index",
        "_id" : "7",
        "_score" : 1.0,
        "_source" : {
          "doc" : {
            "title" : "document 7"
          }
        }
      },
      {
        "_index" : "my_index",
        "_id" : "8",
        "_score" : 1.0,
        "_source" : {
          "doc" : {
            "title" : "document 8"
          }
        }
      }
    ]
  }
}