ElasticSearch經常使用操做：索引篇

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0 說明

基於es 5.4和5.6，參考兩份資料，《從Lucene到Elasticsearch全文檢索實戰》和官方文檔

https://www.elastic.co/guide/en/elasticsearch/reference/5.4/indices.html （官方文檔至關精彩，不容錯過！）。

1 建立索引

PUT my_index

Note1：索引不能有大寫字母；

Note2：es默認給索引設置5個分片1個副本；

NOte3：索引分片數一經指定後不能再修改，但副本數能夠經過命令隨時修改；

能夠添加settings配置：

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

2 更新索引副本數

PUT my_index/_settings
{
  "number_of_replicas": 2
}

3 讀寫權限設置

權限參數以下：

參數設置	說明
blocks.read_only:true	爲true時，設置當前索引只容許讀不容許寫或者更新
blocks.read:true	爲true時，禁止對當前索引進行讀操做
blocks.write:true	爲true時，禁止對當前索引進行寫操做

好比要禁止用戶進行寫操做：

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

再寫入數據時，就會返回403錯誤。

恢復寫操做：

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

4 查看索引

GET my_index/_mapping

返回結果：

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

同時查看多個索引的setting信息：

GET my_index,my_index2/_mapping

查看集羣中全部索引的setting信息：

GET _all/_settings

5 刪除索引

DELETE my_index

若是刪除的索引不存在，會報索引未找到異常。

6 索引的打開與關閉

索引關閉之後就幾乎不會佔用系統資源。

POST my_index/_close

關閉多個索引：

POST my_index,my_index2/_close

加上ignore_unavailable參數：

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

my_index3是不存在的，若是不加ignore_unavailable參數，則會拋出索引不存在錯誤。

關閉集羣中全部索引：

POST _all/_close

以能配符方式關閉索引，關閉以test開頭的索引：

POST test*/_close

7 複製索引

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

Note1：目標索引不會複製源索引中的配置信息，_redinx操做以前須要設置目標索引的分片數、副本數等信息，若是沒有設置，或者說原來就不存在my_index3，那麼會新建立一個索引，而且使用默認配置信息；

Note2：_reindex其實是用來複制索引文檔的，所以若是my_index中沒有文檔，那麼是不會新建立my_index3的；

能夠在source中增長type和query來限制複製的文檔：

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

8 收縮索引

直接參考官方文檔：https://www.elastic.co/guide/en/elasticsearch/reference/5.4/indices-shrink-index.html，很是詳細。

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.

收縮索引前的準備：

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

進行索引的收縮：

POST my_source_index/_shrink/my_target_index

也能夠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": {}
  }
}

若是不太理解的話，就必定要好好閱讀上面提供的官方文檔連接。

9 索引別名

建立索引別名：

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

移除索引別名：

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

Note1：一個索引能夠有多個別名（添加屢次就能夠了），一個別名也能夠對應多個索引（使用屢次就能夠了）；

Note2：在使用別名的時候須要注意，若是別名和索引是一對一的，使用別名索引或者根據ID查詢文檔是能夠的，可是若是別名和索引是一對多的，使用別名會發生錯誤，由於Elasticsearch不知道把文檔寫入哪一個索引中去或者從哪一個索引中讀取文檔；

查看某一個索引的別名：

GET my_index3/_aliases

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

查看一個別名所對應的索引：

GET alias_test/_aliases

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

查看集羣上全部的可用別名：

GET _all/_aliases
或
GET _aliases