ElasticSearch经常使用操做：索引篇

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0 说明

基于es 5.4和5.6，参考两份资料，《从Lucene到Elasticsearch全文检索实战》和官方文档

https://www.elastic.co/guide/en/elasticsearch/reference/5.4/indices.html （官方文档至关精彩，不容错过！）。

1 建立索引

PUT my_index

Note1：索引不能有大写字母；

Note2：es默认给索引设置5个分片1个副本；

NOte3：索引分片数一经指定后不能再修改，但副本数能够经过命令随时修改；

能够添加settings配置：

PUT my_index
{
  "settings": {
    "number_of_shards": 3,
    "number_of_replicas": 1
  }
}

2 更新索引副本数

PUT my_index/_settings
{
  "number_of_replicas": 2
}

3 读写权限设置

权限参数以下：

参数设置	说明
blocks.read_only:true	为true时，设置当前索引只容许读不容许写或者更新
blocks.read:true	为true时，禁止对当前索引进行读操做
blocks.write:true	为true时，禁止对当前索引进行写操做

好比要禁止用户进行写操做：

PUT my_index/_settings
{
  "blocks.write": true
}

再写入数据时，就会返回403错误。

恢复写操做：

PUT my_index/_settings
{
  "blocks.write": false
}

4 查看索引

GET my_index/_mapping

返回结果：

{
  "my_index": {
    "mappings": {
      "my_type": {
        "properties": {
          "title": {
            "type": "text",
            "fields": {
              "keyword": {
                "type": "keyword",
                "ignore_above": 256
              }
            }
          }
        }
      }
    }
  }
}

同时查看多个索引的setting信息：

GET my_index,my_index2/_mapping

查看集群中全部索引的setting信息：

GET _all/_settings

5 删除索引

DELETE my_index

若是删除的索引不存在，会报索引未找到异常。

6 索引的打开与关闭

索引关闭之后就几乎不会占用系统资源。

POST my_index/_close

关闭多个索引：

POST my_index,my_index2/_close

加上ignore_unavailable参数：

POST my_index,my_index2,my_index3/_close?ignore_unavailable=true

my_index3是不存在的，若是不加ignore_unavailable参数，则会抛出索引不存在错误。

关闭集群中全部索引：

POST _all/_close

以能配符方式关闭索引，关闭以test开头的索引：

POST test*/_close

7 复制索引

POST _reindex
{
  "source":{"index":"my_index"},
  "dest":{"index":"my_index3"}
}

Note1：目标索引不会复制源索引中的配置信息，_redinx操做以前须要设置目标索引的分片数、副本数等信息，若是没有设置，或者说原来就不存在my_index3，那么会新建立一个索引，而且使用默认配置信息；

Note2：_reindex其实是用来复制索引文档的，所以若是my_index中没有文档，那么是不会新建立my_index3的；

能够在source中增长type和query来限制复制的文档：

POST _reindex
{
  "source":{
    "index":"my_index",
    "type":"my_type",
    "query":{
      "term":{"title":"elasticsearch"}
    }
  },
  "dest":{"index":"my_index3"}
}

8 收缩索引

直接参考官方文档：https://www.elastic.co/guide/en/elasticsearch/reference/5.4/indices-shrink-index.html，很是详细。

The shrink index API allows you to shrink an existing index into a new index with fewer primary shards. The requested number of primary shards in the target index must be a factor of the number of shards in the source index. For example an index with 8 primary shards can be shrunk into 4, 2or 1 primary shards or an index with 15 primary shards can be shrunk into 5, 3 or 1. If the number of shards in the index is a prime number it can only be shrunk into a single primary shard. Before shrinking, a (primary or replica) copy of every shard in the index must be present on the same node.

Shrinking works as follows:

• First, it creates a new target index with the same definition as the source index, but with a smaller number of primary shards.
• Then it hard-links segments from the source index into the target index. (If the file system doesn’t support hard-linking, then all segments are copied into the new index, which is a much more time consuming process.)
• Finally, it recovers the target index as though it were a closed index which had just been re-opened.

收缩索引前的准备：

PUT /my_source_index/_settings
{
  "settings": {
    "index.routing.allocation.require._name": "shrink_node_name", 
    "index.blocks.write": true 
  }
}

进行索引的收缩：

POST my_source_index/_shrink/my_target_index

也能够添加其它一些配置信息：

POST my_source_index/_shrink/my_target_index
{
  "settings": {
    "index.number_of_replicas": 1,
    "index.number_of_shards": 1, 
    "index.codec": "best_compression" 
  },
  "aliases": {
    "my_search_indices": {}
  }
}

若是不太理解的话，就必定要好好阅读上面提供的官方文档连接。

9 索引别名

建立索引别名：

POST _aliases
{
  "actions": [
    {
      "add": {
        "index": "test1",
        "alias": "alias1"
      }
    }
  ]
}

移除索引别名：

POST _aliases
{
  "actions": [
    {
      "remove": {
        "index": "test1",
        "alias": "alias1"
      }
    }
  ]
}

Note1：一个索引能够有多个别名（添加屡次就能够了），一个别名也能够对应多个索引（使用屡次就能够了）；

Note2：在使用别名的时候须要注意，若是别名和索引是一对一的，使用别名索引或者根据ID查询文档是能够的，可是若是别名和索引是一对多的，使用别名会发生错误，由于Elasticsearch不知道把文档写入哪一个索引中去或者从哪一个索引中读取文档；

查看某一个索引的别名：

GET my_index3/_aliases

结果：
{
  "my_index3": {
    "aliases": {
      "alias_test": {},
      "alias_test2": {}
    }
  }
}

查看一个别名所对应的索引：

GET alias_test/_aliases

结果：
{
  "my_index3": {
    "aliases": {
      "alias_test": {},
      "alias_test2": {}
    }
  },
  "my_index2": {
    "aliases": {
      "alias_test": {}
    }
  },
  "my_index": {
    "aliases": {
      "alias_test": {}
    }
  }
}

查看集群上全部的可用别名：

GET _all/_aliases
或
GET _aliases