当我们使用带有限制选项的count时，为什么mongo db（版本3.0.6）返回错误的记录数？

Question

As per mongo db doc says we can use count with limit.

Limit option is used to specify the maximum number of documents the cursor will return. But if we use limit with count it returns total count and not correct count.

Why?

Suppose we have 50 records in collection then only count option will return 50, and if we apply limit(10) option then it should return 10 and not 50. But count with limit returns 50.

Answer 1

db.collection.find(<query>).count();

You will get count of all records found after executing the query. ie count=50;

db.collection.find(<query>).limit(10).count(true);

You will get the count of limited documents. ie count=10.

You should set applySkipLimit to true.

http://docs.mongodb.org/manual/reference/method/cursor.count/