mongodb文档分组

我的测试集如下所示

> db.test.find()
{ "_id" : "111-21212121", "Mawb" : "111-1111111", "Hawb" : "111111", "Hawb_date" : "date1" }
{ "_id" : "111-21212122", "Mawb" : "111-1111111", "Hawb" : "222222", "Hawb_date" : "date1" }
{ "_id" : "111-21212123", "Mawb" : "222-2222222", "Hawb" : "333333", "Hawb_date" : "date1" }
{ "_id" : "111-21212124", "Mawb" : "222-2222222", "Hawb" : "444444", "Hawb_date" : "date1" }
{ "_id" : "111-21212125", "Mawb" : "333-3333333", "Hawb" : "555555", "Hawb_date" : "date1" }
{ "_id" : "111-21212126", "Mawb" : "333-3333333", "Hawb" : "666666", "Hawb_date" : "date1" }

我想通过“Mawb”键对它进行分组（映射/组合）。。。 这样我就可以有分组文档的输出，比如

[
{ "_id" : "111-21212121", "Mawb" : "111-1111111", "Hawb" : "111111", "Hawb_date" : "date1" }
{ "_id" : "111-21212122", "Mawb" : "111-1111111", "Hawb" : "222222", "Hawb_date" : "date1" }],
[{ "_id" : "111-21212123", "Mawb" : "222-2222222", "Hawb" : "333333", "Hawb_date" : "date1" }
{ "_id" : "111-21212124", "Mawb" : "222-2222222", "Hawb" : "444444", "Hawb_date" : "date1" }],
[{ "_id" : "111-21212125", "Mawb" : "333-3333333", "Hawb" : "555555", "Hawb_date" : "date1" }
{ "_id" : "111-21212126", "Mawb" : "333-3333333", "Hawb" : "666666", "Hawb_date" : "date1" }]

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我试过要一张地图，但打不通。我该怎么做呢？

如果您使用的是MongoDB 2.1或更高版本（2.1.x是即将推出2.2.0稳定版的开发系列），那么您可以使用聚合框架在服务器端完成所有这一切