ElasticSearch之通过update_by_query和

ElasticSearch之通过update_by_query和_reindex重建索引

news2025/1/11 17:01:21

写在前面

当我们索引的mapping，setting发生变更时，我们需要重建索引来使得这些变更生效。es提供了两种方式来完成重建索引的操作：

1:update by query,在本索引重建
2：reindex，在新索引上重建

我们通过具体实例来分别看下。

1：增加子字段

核心点，如果不执行update_by_query，修改mapping前将会无法查询到。执行update_by_query的方式如下：

POST {索引名称}/_update_by_query
{
  
}

具体实例(从上往下看即可):

# 1：创建索引，指定mapping
DELETE blogs

PUT blogs
{
  "mappings": {
    "properties": {
      "content": {
        "type": "text"
      },
      "keyword": {
        "type": "text"
      }
    }
  }
}

# 2：修改mapping前插入一条数据
PUT blogs/_doc/1
{
  "content": "Hadoop is coll",
  "keyword": "Hadoop"
}

# 3：修改mapping，增加子字段english
PUT blogs/_mapping
{
  "properties": {
    "content": {
      "type": "text",
      "fields": {
        "english": {
          "type": "text",
          "analyzer": "english"
        }
      }
    },
    "keyword": {
      "type": "text"
    }
  }
}

# 4:修改mapping后插入一条记录
PUT blogs/_doc/2
{
  "content": "Elasticsearch is hard to study,but i will keep up",
  "keyword": "Elasticsearch"
}

# 5:查询修改mapping前的数据，查询不到
POST blogs/_search
{
  "query": {
    "match": {
      "content.english": "Hadoop"
    }
  }
}

# 6:查询修改mapping后的数据，可以查询到
POST blogs/_search
{
  "query": {
    "match": {
      "content.english": "Elasticsearch"
    }
  }
}

# 7：执行update_by_query，重建本索引
POST blogs/_update_by_query
{
  
}

# 8:再次查询修改mapping前的数据，就可以查询到了
POST blogs/_search
{
  "query": {
    "match": {
      "content.english": "Hadoop"
    }
  }
}

2：修改字段类型

es不允许修改字段类型，想要完成修改字段类型操作的话必须使用reindex。

# 1：创建索引，指定mapping，注意此时keyword字段是text类型
DELETE blogs

PUT blogs
{
  "mappings": {
    "properties": {
      "content": {
        "type": "text"
      },
      "keyword": {
        "type": "text"
      }
    }
  }
}

# 2：插入几条测试数据
POST blogs/_bulk
{"index": {"_id": 1}}
{"content":"Hadoop is coll","keyword":"Hadoop"}
{"index": {"_id": 2}}
{"content":"Elasticsearch is hard to study,but i will keep up","keyword":"Elasticsearch"}

# 3:尝试修改keyword的数据类型从text为keyword，会报错
# mapper [keyword] of different type, current_type [text], merged_type [keyword]
PUT blogs/_mapping
{
  "properties": {
    "content": {
      "type": "text"
    },
    "keyword": {
      "type": "keyword"
    }
  }
}

# 4：创建全新的索引,但是指定keyword字段类型为keyword
DELETE blogs_fix

PUT blogs_fix
{
  "mappings": {
    "properties": {
      "content": {
        "type": "text"
      },
      "keyword": {
        "type": "keyword"
      }
    }
  }
}

# 5：通过reindex拷贝数据到新索引
POST _reindex
{
  "source": {
    "index": "blogs"
  },
  "dest": {
    "index": "blogs_fix"
  }
}

# 6：看是否成功 "count" : 2即为成功了
GET blogs_fix/_count

# 7:对keyword字段执行term agg，可以成功，进一步验证其字段类型是keyword（因为textfielddata默认是关闭的无法term）
GET blogs_fix/_search
{
  "aggs": {
    "term分组验证就是keyword类型": {
      "terms": {
        "field": "keyword"
      }
    }
  }
}