Elasticsearch之mapping

1, Government Bunkaji Site
2, Character type

1, 定义: Mapping is the process of defining how documents and the fields they contain are stored and indexed.
2. Each document is a collection of fields, and each field has its own data type.
3. When mapping data, you can create a mapping definition that contains a list of fields related to the document
4. The mapping definition also includes metadata fields, such as The _source field, which customizes how the document's associated metadata is processed.
5. You can use 动态映射 and 显式映射 to define data.

Create a mapping explicitly

Explicit mapping allows you to choose exactly how to define the mapping, for example:

• Which string fields should be considered full-text fields.
• Which fields contain numbers, dates, or locations.
• The format of the date value.
• Customize rules to control mapping of dynamically added fields.

Explicitly create the mapping; that is, create it by defining a custom mapping before adding data to the index

PUT /my-index-000001
{
    
    
  "mappings": {
    
    
    "properties": {
    
    
      "age":    {
    
     "type": "integer" },  
      "email":  {
    
     "type": "keyword"  }, 
      "name":   {
    
     "type": "text"  }     
    }
  }
}

View the mapping definition of a specific index

GET index_name/_mapping

GET bank/_mapping

You can see the field types defined in mapping, where account_number is long type, address field is full-text search, and it also defines that the following keyword attribute is a keyword type, that is, inseparable words. This also explains very welladdress.keywordwhy it is an exact match

Add a new attribute to an existing mapping

The mapping information has been defined for the indexmy-index-000001 before, as follows

PUT /my-index-000001
{
    
    
  "mappings": {
    
    
    "properties": {
    
    
      "age":    {
    
     "type": "integer" },  
      "email":  {
    
     "type": "keyword"  }, 
      "name":   {
    
     "type": "text"  }     
    }
  }
}

Now I want to add a new attribute to itemployee_id. How to do it? As shown in the code snippet below

PUT /my-index-000001/_mapping
{
    
    
  "properties": {
    
    
    "employee-id": {
    
    
      "type": "keyword",
      "index": false
    }
  }
}

where"index": false indicates that the current field cannot be indexed; thisindex和type一样都叫 mapping parameters, is the entrance to the official document a>

View the definition information of the specified field in the mapping

For example, if you only want to view the definition information of the field in my-index-000001, you can use the following commandemployee_id

GET /my-index-000001/_mapping/field/employee-id

The API response results are as follows:

{
    
    
  "my-index-000001" : {
    
    
    "mappings" : {
    
    
      "employee-id" : {
    
    
        "full_name" : "employee-id",
        "mapping" : {
    
    
          "employee-id" : {
    
    
            "type" : "keyword",
            "index" : false
          }
        }
      }
    }
  }
}

Update a field that already has a mapping

This section only makes simple records. For specific operations, read the official documentation to find the corresponding solution.

The official statement clearly states:除了支持的映射参数外，您不能更改现有字段的映射或字段类型。更改现有字段可能会使已经索引的数据无效;如果需要更改索引中字段的映射，请创建具有正确映射的新索引，并将数据重新索引到该索引中。

• Cannot directly modify existing mappings
• Redefine a correct mapping
• UsereindexMigrate data

The official mentioned a term here reindx , which is also a specific solution for updating a certain field in the mapping