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Set Missing Shard Key Fields设置缺失的分片关键点字段

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If you have missing shard key fields, you can set the shard key field to null. 如果缺少分片键字段，可以将分片键域设置为null。If you want to set the missing shard key field to a non-null value, see Change a Document's Shard Key Value.如果您想将缺少的分片键字段设置为非null值，请参阅更改文档的分片键值。

To perform the update, you can use the following operations on a mongos:要执行更新，您可以在mongos上使用以下操作：

Command命令Method方法Description描述
update with multi: true使用multi: true更新db.collection.updateMany()
  • Can be used to set the missing key value to null only.只能用于将缺少的键值设置为null。
  • Can be performed inside or outside a transaction.可以在事务内部或外部执行。
  • Can be performed as a retryable write or not.是否可以作为可重试写入执行。
  • For additional requirements, refer to the specific command/method.有关其他要求，请参阅特定命令/方法。
update with multi: false使用multi: false更新db.collection.replaceOne()
db.collection.updateOne()
  • Can be used to set the missing key value to null or any other value.可用于将缺少的键值设置为null或任何其他值。
  • The update to set missing shard key fields must meet one of the following requirements:设置缺少的分片键字段的更新必须满足以下要求之一：
    • the filter of the query contains an equality condition on the full shard key in the query查询的筛选器包含查询中完整分片键的相等条件
    • the filter of the query contains an exact match on _id查询的筛选器包含_id上的完全匹配
    • the update targets a single shard更新针对单个分片
  • To set to a non-null value, refer to Change a Document's Shard Key Value.要设置为非null值，请参阅更改文档的分片键值。
  • For additional requirements, refer to the specific command/method.有关其他要求，请参阅特定命令/方法。
findAndModifydb.collection.findOneAndReplace()
db.collection.findOneAndUpdate()
db.collection.findAndModify()
  • Can be used to set the missing key value to null or any other value.可用于将缺少的键值设置为null或任何其他值。
  • When setting missing shard key fields with a method that explicitly updates only one document, the update must meet one of the following requirements:当使用只显式更新一个文档的方法设置缺少的分片键字段时，更新必须满足以下要求之一：
    • the filter of the query contains an equality condition on the full shard key in the query查询的筛选器包含查询中完整分片键的相等条件
    • the filter of the query contains an exact match on _id查询的筛选器包含_id上的完全匹配
    • the update targets a single shard更新针对单个分片
  • Missing key values are returned when matching on null. 在null上匹配时返回缺少的键值。To avoid updating a key value that is null, include additional query conditions as appropriate.为了避免更新为null的键值，请酌情包含其他查询条件。
  • To set to a non-null value, refer to Change a Document's Shard Key Value.要设置为非null值，请参阅更改文档的分片键值。
  • For additional requirements, refer to the specific command/method.有关其他要求，请参阅特定命令/方法。
db.collection.bulkWrite()
Bulk.find.replaceOne()
Bulk.find.updateOne()
Bulk.find.update()
  • To set to a null value, you can specify multiple shard key modifications in the bulk operation.要设置为null值，可以在批量操作中指定多个分片键修改。
  • When setting missing shard key fields with a method that explicitly updates only one document, the update must meet one of the following requirements:当使用只显式更新一个文档的方法设置缺少的分片键字段时，更新必须满足以下要求之一：
    • the filter of the query contains an equality condition on the full shard key in the query查询的筛选器包含查询中完整分片键的相等条件
    • the filter of the query contains an exact match on _id查询的筛选器包含_id上的完全匹配
    • the update targets a single shard更新针对单个分片
  • To set to a non-null value, refer to Change a Document's Shard Key Value.要设置为非null值，请参阅更改文档的分片键值。
  • For additional requirements, refer to the underlying command/method.有关其他要求，请参阅底层命令/方法。

Example实例

Consider a sales collection which is sharded on the location field. 考虑一个销售集合，它在location字段上进行了分片。Some documents in the collection have no location field. A missing field is considered the same as a null value for the field. 集合中的某些文档没有location字段。缺少的字段被认为与字段的空值相同。To explicitly set these fields to null, run the following command:要将这些字段显式设置为null，请运行以下命令：

db.sales.updateOne(
  { _id: 12345, location: null },
  { $set: { location: null } }
)

When setting missing shard key fields with db.collection.updateOne() or another method that explicitly updates only one document, the update must meet one of the following requirements:当使用db.collection.updateOne()或其他只显式更新一个文档的方法设置缺少的分片键字段时，更新必须满足以下要求之一：

  • the filter of the query contains an equality condition on the full shard key in the query查询的筛选器包含查询中完整分片键的相等条件
  • the filter of the query contains an exact match on _id查询的筛选器包含_id上的完全匹配
  • the update targets a single Shard更新针对单个分片