To avoid these situations, on a sharded cluster, use the $group stage of the db.collection.aggregate() method to $sum the documents. For example, the following operation counts the documents in a collection: 为了避免分片集群发生这种情况,使用db.collection.aggregate()命令中的$group方法进行文档$su...
The count method is deprecated and should be replaced by the countDocuments or estimatedDocumentCount method
而MongoDB3.6官方文档却是这么描述的 On a sharded cluster, db.collection.count() can result in an inaccurate count if orphaned documents exist or if a chunk migration is in progress. To avoid these situations, on a sharded cluster, use the db.collection.aggregate() method 也就是说,MongoDB4.0...
db.collection.find(<query>).count() count()方法具有以下参数: Parameter 类型 说明 applySkipLimit 布尔 Optional. Specifies whether to consider the effects of thecursor.skip()andcursor.limit()methods in the count. By default, thecount()method ignores the effects of thecursor.skip()andcursor.limi...
通过谷歌发现,官方文档——(https://docs.mongodb.com/manual/reference/method/db.collection.count/)中有解释这种现象: On a sharded cluster, db.collection.count() can result in an inaccurate count if orphaned documentsexist or if a chunk migration is in progress. ...
in MongoDB is an array, which can store multiple values in a single field. When working with arrays in MongoDB, you may need to query and count the number of elements in an array. In this article, we will explore how to perform an array count query in MongoDB using thecountmethod. ...
By default, the count() method ignores the effects of the cursor.skip() and cursor.limit(). Set applySkipLimit to true to consider the effect of these methods. MongoDB 提供了与 db.collection.count() 方法效果相同的 db.collection.find(<query>).count() 方法,可以任选一个使用。 参见 cursor...
To avoid these situations, on a sharded cluster, use the db.collection.aggregate() method 也就是说,MongoDB4.0分片集群模式下,针对不带谓词条件的全表count操作的返回结果是不准确的,主要包括以下两种场景。在MongoDB4.0以前的版本,即使不带谓词条件,在以下两种场景下count值也不准。
db.table3.count() 使用该命令依然会出现统计信息不准确的现象,通过谷歌发现,官方文档——(https://docs.mongodb.com/manual/reference/method/db.collection.count/)中有解释这种现象: On a sharded cluster,db.collection.count()can result in aninaccuratecount iforphaned documentsexist or if achunk migration...
参考: mongo 官方文档: cursor.count() : applySkipLimit: booleanOptional. Specifies whether to consider the effects of the cursor.skip() and cursor.limit() methods in the count. By default, the count() method ignores the effects of the cursor.skip() and cursor.limit(). Set applySkipLimit...