Database Manual / Indexes / Create

Specify an Index Name指定索引名称

When you create an index, you can give the index a custom name. Giving your index a name helps distinguish different indexes on your collection. 创建索引时，可以为索引提供自定义名称。为索引命名有助于区分集合中的不同索引。For example, you can more easily identify the indexes used by a query in the query plan's explain results if your indexes have distinct names.例如，如果索引具有不同的名称，则可以更容易地在查询计划的解释结果中识别查询使用的索引。

To specify the index name, include the name option when you create the index:要指定索引名称，请在创建索引时包含name选项：

db.<collection>.createIndex(
   { <field>: <value> },
   { name: "<indexName>" }
)

About this Task关于此任务

Before you specify an index name, consider the following:在指定索引名称之前，请考虑以下事项：

  • Index names must be unique. Creating an index with the name of an existing index returns an error.索引名称必须唯一。使用现有索引的名称创建索引会返回错误。
  • You can't rename an existing index. Instead, you must drop and recreate the index with a new name.您不能重命名现有索引。相反，您必须删除索引并用新名称重新创建。

Default Index Names默认索引名称

If you don't specify a name during index creation, the system generates the name by concatenating each index key field and value with underscores. For example:如果在创建索引时没有指定名称，系统将通过用下划线连接每个索引键字段和值来生成名称。例如：

Index索引Default Name默认名称
{ score : 1 }score_1
{ content : "text", "description.tags": "text" }content_text_description.tags_text
{ category : 1, locale : "2dsphere"}category_1_locale_2dsphere
{ "fieldA" : 1, "fieldB" : "hashed", "fieldC" : -1 }fieldA_1_fieldB_hashed_fieldC_-1

Procedure过程

A blog collection contains data about blog posts and user interactions.blog集合包含有关博客帖子和用户交互的数据。

Create a text index on the content, users.comments, and users.profiles fields. Set the index name to InteractionsTextIndex:在content、users.comments和users.profiles文件字段上创建文本索引。将索引name设置为InteractionsTextIndex：

db.blog.createIndex(
   {
     content: "text",
     "users.comments": "text",
     "users.profiles": "text"
   },
   {
     name: "InteractionsTextIndex"
   }
)

Results结果

After you create the index, you can use the db.collection.getIndexes() method to get the index name:创建索引后，可以使用db.collection.getIndexes()方法获取索引名称：

db.blog.getIndexes()

Output:输出：

[
  { v: 2, key: { _id: 1 }, name: '_id_' },
  {
    v: 2,
    key: { _fts: 'text', _ftsx: 1 },
    name: 'InteractionsTextIndex',
    weights: { content: 1, 'users.comments': 1, 'users.profiles': 1 },
    default_language: 'english',
    language_override: 'language',
    textIndexVersion: 3
  }
]

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