上一篇说到如果一个索引的mapping设置过了,想要修改type或analyzer,通常的做法是新建一个索引,重新设置mapping,再把数据同步过来。

那么如何实现零停机时间更新索引配置或迁移索引?这就需要用到索引的别名设置。

思路:

1、假设我们的索引是demo_v1,我们定义了一个别名demo,以后所有的操作都用别名demo操作。

2、现在索引demo_v1的mapping设置或者其他一些设置不满足我们的需求了,我们需要修改。新建一个索引demo_v2,同时设置好最新配置。

3、同步索引demo_v1的数据到索引demo_v2。直到同步完。

4、移除索引demo_v1的别名demo,同时设置索引demo_v2的别名为demo。

5、删除索引demo_v1。

6、迁移完成。以后如果还有设置变更,可以按照这个思路继续设置索引demo_v3、demo_v4……

接下来用一个例子说明实现过程,实际项目中我也是按这个思路做的。如果有一些命令操作看不懂,可参看上一篇文章。

1、创建索引demo_v1

> curl -XPUT 'localhost:9200/demo_v1'   
{"acknowledged":true,"shards_acknowledged":true}%

2、给索引demo_v1添加几条数据

#给索引demo_v1添加了type=fruit的3条数据,每条数据用name和tag两个字段
> curl -XPOST 'localhost:9200/_bulk?pretty' -d' { "index" : { "_index" : "demo_v1", "_type" : "fruit", "_id" : "1" }} { "name" : "苹果","tag":"苹果,水果,红富士"} { "create" : { "_index" : "demo_v1", "_type" : "fruit", "_id" : "2" }} { "name" : "香蕉","tag":"香蕉,水果,海南,弯弯,小黄人"} { "index" : { "_index" : "demo_v1", "_type" : "fruit", "_id" : "3" }} { "name" : "西瓜","tag":"西瓜,水果,圆形,绿,闰土"} '
#返回 { "took" : 34, "errors" : false, "items" : [ { "index" : { "_index" : "demo_v1", "_type" : "fruit", "_id" : "1", "_version" : 1, "result" : "created", "_shards" : { "total" : 2, "successful" : 1, "failed" : 0 }, "created" : true, "status" : 201 } }, { "create" : { "_index" : "demo_v1", "_type" : "fruit", "_id" : "2", "_version" : 1, "result" : "created", "_shards" : { "total" : 2, "successful" : 1, "failed" : 0 }, "created" : true, "status" : 201 } }, { "index" : { "_index" : "demo_v1", "_type" : "fruit", "_id" : "3", "_version" : 1, "result" : "created", "_shards" : { "total" : 2, "successful" : 1, "failed" : 0 }, "created" : true, "status" : 201 } } ] }

3、给索引demo_v1设置别名demo

#设置别名 
> curl -XPUT 'localhost:9200/demo_v1/_alias/demo' 
{"acknowledged":true}%

4、使用别名查看信息

#使用别名查看一下数据,是可以查询到的 
> curl -XGET 'localhost:9200/demo/fruit/_search?pretty' 
 
#查看mapping 
> curl -XGET 'localhost:9200/demo/fruit/_mapping?pretty' 
#返回 
{ 
  "demo_v1" : { 
    "mappings" : { 
      "fruit" : { 
        "properties" : { 
          "name" : { 
            "type" : "text", 
            "fields" : { 
              "keyword" : { 
                "type" : "keyword", 
                "ignore_above" : 256 
              } 
            } 
          }, 
          "tag" : { 
            "type" : "text", 
            "fields" : { 
              "keyword" : { 
                "type" : "keyword", 
                "ignore_above" : 256 
              } 
            } 
          } 
        } 
      } 
    } 
  } 
} 
 
#检索数据 
> curl -XGET 'http://localhost:9200/demo/fruit/_search?pretty' -d '{ 
    "query" : { 
        "term" : { "tag" : "水" } 
   } 
}' 
#返回 
{ 
  "took" : 1, 
  "timed_out" : false, 
  "_shards" : { 
    "total" : 5, 
    "successful" : 5, 
    "failed" : 0 
  }, 
  "hits" : { 
    "total" : 3, 
    "max_score" : 0.28582606, 
    "hits" : [ 
      { 
        "_index" : "demo_v1", 
        "_type" : "fruit", 
        "_id" : "1", 
        "_score" : 0.28582606, 
        "_source" : { 
          "name" : "苹果", 
          "tag" : "苹果,水果,红富士" 
        } 
      }, 
      { 
        "_index" : "demo_v1", 
        "_type" : "fruit", 
        "_id" : "3", 
        "_score" : 0.27233246, 
        "_source" : { 
          "name" : "西瓜", 
          "tag" : "西瓜,水果,圆形,绿,闰土" 
        } 
      }, 
      { 
        "_index" : "demo_v1", 
        "_type" : "fruit", 
        "_id" : "2", 
        "_score" : 0.24257512, 
        "_source" : { 
          "name" : "香蕉", 
          "tag" : "香蕉,水果,海南,弯弯,小黄人" 
        } 
      } 
    ] 
  } 
}

数据因为先前创建索引时没有设置mapping,所以这些设置都是默认设置,分词器也默认标准分词器。

上面检索标签tag中带有“水”的数据,都查询出来了,说明默认分词器把“水果”这个词拆分了。

如果我们需要tag字段按照逗号分词,“水果”作为一个完整的词不拆分该怎么弄呢?

5、新建一个索引demo_v2,同时自定义逗号分词器,并把逗号分词器应用到tag字段上

#新建索引demo_v2
> curl -XPUT 'http://localhost:9200/demo_v2/' -d'{ "settings": { "index": { "analysis": { "analyzer": { "douhao_analyzer": { "pattern": ",", "type": "pattern" } } }, "number_of_shards": 5, "number_of_replicas": 1 } }, "mappings": { "fruit": { "properties": { "name": { "type": "text", "index": "not_analyzed" }, "tag": { "type": "string", "analyzer": "douhao_analyzer", "search_analyzer": "douhao_analyzer" } } } } }'
#返回 {"acknowledged":true,"shards_acknowledged":true}%

 关于mapping设置及分词器设置可参见官方文档:

 IT虾米网

IT虾米网

6、同步索引demo_v1中的数据到demo_v2

我使用工具elasticdump同步数据,ElasticDump是一个ElasticSearch的数据导入导出开源工具包。

官方地址:IT虾米网

同步命令如下:

> elasticdump --input='http://localhost:9200/demo_v1'  --output='http://localhost:9200/demo_v2' --type=data 
Wed, 21 Jun 2017 09:53:15 GMT | starting dump 
Wed, 21 Jun 2017 09:53:15 GMT | got 3 objects from source elasticsearch (offset: 0) 
Wed, 21 Jun 2017 09:53:15 GMT | sent 3 objects to destination elasticsearch, wrote 3 
Wed, 21 Jun 2017 09:53:15 GMT | got 0 objects from source elasticsearch (offset: 3) 
Wed, 21 Jun 2017 09:53:15 GMT | Total Writes: 3 
Wed, 21 Jun 2017 09:53:15 GMT | dump complete

7、验证一下demo_v2中的数据

#检索tag中包含“水”的数据,检索不到就是正常的 
curl -XGET 'http://localhost:9200/demo_v2/fruit/_search?pretty' -d '{ 
    "query" : { 
        "term" : { "tag" : "水" } 
   } 
}' 
 
#检索tag中包含“水果”的数据,可以全部检索到 
curl -XGET 'http://localhost:9200/demo_v2/fruit/_search?pretty' -d '{ 
    "query" : { 
        "term" : { "tag" : "水果" } 
   } 
}'

8、移除索引demo_v1的别名demo,同时设置索引demo_v2的别名为demo

curl -XPOST 'localhost:9200/_aliases?pretty' -d'{ 
  "actions" : [ 
  { "remove" : { "index" : "demo_v1", "alias" : "demo" } }, 
  { "add" : { "index" : "demo_v2", "alias" : "demo" } } 
]}'

9、删除索引demo_v1

curl -XDELETE 'localhost:9200/demo_v1'

至此整个迁移完成

ok!


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