cursor.hint()

Definition定义

cursor.hint(index)

Important重要

mongosh Method

This is a mongosh method. This is not the documentation for Node.js or other programming language specific driver methods.

In most cases, mongosh methods work the same way as the legacy mongo shell methods. However, some legacy methods are unavailable in mongosh.

For the legacy mongo shell documentation, refer to the documentation for the corresponding MongoDB Server release:

• mongo shell v4.4
• mongo shell v4.2
• mongo shell v4.0

For MongoDB API drivers, refer to the language specific MongoDB driver documentation.

Call this method on a query to override MongoDB's default index selection and query optimization process. 对查询调用此方法以覆盖MongoDB的默认索引选择和查询优化过程。Use db.collection.getIndexes() to return the list of current indexes on a collection.使用db.collection.getIndexes()返回集合上的当前索引列表。

The cursor.hint() method has the following parameter:cursor.hint()方法具有以下参数：

Parameter参数	Type类型	Description描述
index	string or document	The index to "hint" or force MongoDB to use when performing the query. 执行查询时“提示”或强制MongoDB使用的索引。Specify the index either by the index name or by the index specification document.通过索引名称或索引规范文档指定索引。 You can also specify { $natural : 1 } to force the query to perform a forwards collection scan, or { $natural : -1 } for a reverse collection scan.还可以指定{$natural:1}强制查询执行正向集合扫描，或者指定{$natural:-1}执行反向集合扫描。

Behavior行为

• When an index filter exists for the query shape, MongoDB ignores the hint().当查询形状存在索引筛选器时，MongoDB会忽略hint()。
• You cannot use hint() if the query includes a $text query expression.如果查询包含$text查询表达式，则不能使用hint()。
• You cannot use hint() on a hidden index.不能对隐藏索引使用hint()。
• On a time series collections, you can only specify hints using the index name, not the index key pattern.在时间序列集合上，只能使用索引名称而不是索引键模式指定提示。

Examples示例

db.users.find().hint( { age: 1 } )

db.users.find().hint( "age_1" )

db.users.find().hint( { $natural : 1 } )

db.users.find().hint( { $natural : -1 } )