Elasticsearch 7：获取指定 shard 中的文档

#Elasticsearch 笔记

查询条件中追加?preference=_shards:<num> 接口。

示例

数据准备

# 创建索引
PUT student
{
  "mappings" : {
    "properties" : {
      "uid": {
        "type" : "integer"
      },
      "name" : {
        "type" : "keyword"
      },
      "age" : {
        "type" : "integer"
      }
    }
  },
  "settings" : {
    "index" : {
      "number_of_shards" : 10,
      "number_of_replicas" : 1
    }
  }
}

# 插入数据
POST student/_doc/1?routing=1
{
  "uid": 1,
  "name": "张三",
  "age": 10
}

# 插入数据
POST student/_doc/2?routing=2
{
  "uid": 2,
  "name": "张三",
  "age": 10
}

查询数据所在 shard

查询中增加"explain": true 即可。

请求：

GET student/_search
{
  "query": {
    "match_all": {}
  },
  "size": 20, 
  "explain": true
}

响应：

{
  "took" : 137,
  "timed_out" : false,
  "_shards" : {
    "total" : 10,
    "successful" : 10,
    "skipped" : 0,
    "failed" : 0
  },
  "hits" : {
    "total" : {
      "value" : 2,
      "relation" : "eq"
    },
    "max_score" : 1.0,
    "hits" : [
      {
        "_shard" : "[student][7]",   # 所属 shard
        "_node" : "PI2YKOcTToeceMtdvgdUaw",
        "_index" : "student",
        "_type" : "_doc",
        "_id" : "2",
        "_score" : 1.0,
        "_routing" : "2",
        "_source" : {
          "uid" : 2,
          "name" : "张三",
          "age" : 10
        },
        "_explanation" : {
          "value" : 1.0,
          "description" : "*:*",
          "details" : [ ]
        }
      },
      {
        "_shard" : "[student][8]",
        "_node" : "PI2YKOcTToeceMtdvgdUaw",
        "_index" : "student",
        "_type" : "_doc",
        "_id" : "1",
        "_score" : 1.0,
        "_routing" : "1",
        "_source" : {
          "uid" : 1,
          "name" : "张三",
          "age" : 10
        },
        "_explanation" : {
          "value" : 1.0,
          "description" : "*:*",
          "details" : [ ]
        }
      }
    ]
  }
}

查询指定 shard 中的数据

请求：

GET student/_search?preference=_shards:1
{
  "query": {
    "match_all": {}
  },
  "size": 20
}

响应为空。

请求：

GET student/_search?preference=_shards:7
{
  "query": {
    "match_all": {}
  },
  "size": 20
}

响应：

{
  "took" : 0,
  "timed_out" : false,
  "_shards" : {
    "total" : 1,
    "successful" : 1,
    "skipped" : 0,
    "failed" : 0
  },
  "hits" : {
    "total" : {
      "value" : 1,
      "relation" : "eq"
    },
    "max_score" : 1.0,
    "hits" : [
      {
        "_index" : "student",
        "_type" : "_doc",
        "_id" : "2",
        "_score" : 1.0,
        "_routing" : "2",
        "_source" : {
          "uid" : 2,
          "name" : "张三",
          "age" : 10
        }
      }
    ]
  }
}