在Mongo 2.6和Pymongo 2.7.1上将maxTimeMS参数与聚合查询一起使用 [英] Using maxTimeMS parameter with aggregation queries on Mongo 2.6 and Pymongo 2.7.1

问题描述

• 我无法在Mongo 2.6和Pymongo 2.7.1中使用maxTimeMS参数

• I'm unable to use maxTimeMS parameter with Mongo 2.6 and Pymongo 2.7.1

根据此页面上的文档

As per the documentation on this page Official Mongodb Aggregation Page the aggregation method should return a Cursor object. However, when I run the query locally on a mongod instance (2.6+) with pymongo 2.7.1, I get a dict object!

在[14]中:obj = coll.aggregate({'$ group':{'_id':'$ l'，'n':{'$ sum': 1}}})

In [14]: obj = coll.aggregate({'$group': {'_id': '$l', 'n': {'$sum': 1}}})

在[15]中:键入(obj)在[15]中:字典

In [15]: type(obj) Out[15]: dict

有人可以帮助我了解这里发生的事情吗?

Can anyone help me understand what is happening here?

推荐答案

是的，您可以将maxTimeMS与pymongo聚合一起使用.

Yes, you can use maxTimeMS with pymongo aggregation.

c.foo.bar.aggregate([], maxTimeMS=1000)
{u'ok': 1.0, u'result': []}

如果要使用光标:

for result in c.foo.bar.aggregate([], cursor={}, maxTimeMS=1000):
... print result

在MongoDB 2.6之前，aggregate命令不支持游标，因此必须将其添加为一个选项，以避免破坏现有应用程序.

The aggregate command didn't support cursors before MongoDB 2.6 so it had to be added as an option to avoid breaking existing applications.

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