Elasticsearch

Elasticsearch 介绍 Elasticsearch 7:快速上手 Elasticsearch 7:关于 Index、Type、Document Elasticsearch 7:安装与启动 Elasticsearch 7:Kibana 的使用 Elasticsearch 7:下载历史版本 Elasticsearch 7:文档唯一性 Elasticsearch 7:默认端口与端口设置 Elasticsearch 7:创建和删除索引 Elasticsearch 7:自定义 mapping 和 settings Elasticsearch 7:设置索引副本数量和分片数量 Elasticsearch 7:查看所有索引 Elasticsearch 7:数据类型 Elasticsearch 7:字符串类型 keyword 、text Elasticsearch 7:数组 Elasticsearch 7:添加和更新文档 Elasticsearch 7:通过 _bulk 批量添加文档 Elasticsearch 7:使用 from 、size 进行分页查询 Elasticsearch 7:查询中使用 sort 进行排序 Elasticsearch 7:查询结果只展示部分字段 Elasticsearch 7:查询结果中展示 _version 字段 Elasticsearch 7:使用 ignore_above 限制字符串长度 Elasticsearch 7:动态映射 Elasticsearch 7:doc_values 属性 Elasticsearch 7:刷新周期 refresh_interval Elasticsearch 7:使用 _refresh 刷新索引 Elasticsearch 7:分片(shard)限制 Elasticsearch 7:使用 _cat thread_pool 查询线程池运行情况 Elasticsearch 7:事务日志 translog Elasticsearch 7:文档 _id 的长度限制 Elasticsearch 7:分片 shard Elasticsearch 7:滚动查询 Elasticsearch 7:聚合查询 Elasticsearch 7:索引模板 Elasticsearch 7:获取文档所属的 shard Elasticsearch 7:获取版本号 Elasticsearch 7:获取指定 shard 中的文档 Elasticsearch 7:获取 shard 统计信息 Elasticsearch 7:搜索实战 Elasticsearch 7:Python 客户端 Elasticsearch 7:Java TransportClient API 客户端 Elasticsearch 7:Java REST Client API 客户端 Elasticsearch:将 SQL 转换为 DSL Elasticsearch 6 快速上手 Elasticsearch 5 快速上手 Elasticsearch 5:禁止自动创建索引 Elasticsearch 5:禁止动态增加字段 Elasticsearch 产品版本支持周期 基于 Elasticsearch 的站内搜索引擎实战

Elasticsearch 7:分片 shard


#Elasticsearch


创建索引时指定多个分片

示例:

PUT student
{
  "mappings" : {
    "properties" : {
      "name" : {
        "type" : "keyword"
      }
    }
  },
  "settings" : {
    "index" : {
      "number_of_shards" : 8
    }
  }
}

哈希算法

按照官方的讨论 ,使用了 murmur3 哈希算法。 作为 ES 使用者,不需要关注具体的算法,因为不保证以后不会换成其他的算法。

routing 参数

在文档相关的增删改查API 中,均可指定 routing 参数进行分片路由。

查询结果中展示文档所属分片

创建索引:

PUT student
{
  "mappings" : {
    "properties" : {
      "name" : {
        "type" : "keyword"
      }
    }
  },
  "settings" : {
    "index" : {
      "number_of_shards" : 8
    }
  }
}

插入数据时指定 routing 用于路由分片:

POST student/_doc/1?routing=1
{
  "name": "name01"
}

POST student/_doc/2?routing=abc
{
  "name": "name02"
}

在查询中指定 explain 为 true,可以看到文档的 shard 信息:

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

结果:

{
  "took" : 1,
  "timed_out" : false,
  "_shards" : {
    "total" : 8,
    "successful" : 8,
    "skipped" : 0,
    "failed" : 0
  },
  "hits" : {
    "total" : {
      "value" : 2,
      "relation" : "eq"
    },
    "max_score" : 1.0,
    "hits" : [
      {
        "_shard" : "[student][0]",
        "_node" : "wFhSfuLwR3OX21eldbRIHg",
        "_index" : "student",
        "_type" : "_doc",
        "_id" : "1",
        "_score" : 1.0,
        "_routing" : "1",
        "_source" : {
          "name" : "name01"
        },
        "_explanation" : {
          "value" : 1.0,
          "description" : "*:*",
          "details" : [ ]
        }
      },
      {
        "_shard" : "[student][5]",
        "_node" : "wFhSfuLwR3OX21eldbRIHg",
        "_index" : "student",
        "_type" : "_doc",
        "_id" : "2",
        "_score" : 1.0,
        "_routing" : "abc",
        "_source" : {
          "name" : "name02"
        },
        "_explanation" : {
          "value" : 1.0,
          "description" : "*:*",
          "details" : [ ]
        }
      }
    ]
  }
}

查询每个分片的信息

示例:

GET /student/_search_shards

如何指定查询某个分片中的数据

查询 shard 0 :

GET student/_search?preference=_shards:0

结果:

{
  "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" : "1",
        "_score" : 1.0,
        "_routing" : "1",
        "_source" : {
          "name" : "name01"
        }
      }
    ]
  }
}

查询 shard 1:

GET student/_search?preference=_shards:1

结果:

{
  "took" : 0,
  "timed_out" : false,
  "_shards" : {
    "total" : 1,
    "successful" : 1,
    "skipped" : 0,
    "failed" : 0
  },
  "hits" : {
    "total" : {
      "value" : 0,
      "relation" : "eq"
    },
    "max_score" : null,
    "hits" : [ ]
  }
}


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