MongoDB去重

db.集合.aggregate([
    {
        $group: { _id: {字段1: '$字段1',字段2: '$字段2'},count: {$sum: 1},dups: {$addToSet: '$_id'}}
    },
    {
        $match: {count: {$gt: 1}}
    }
]).forEach(function(doc){
    doc.dups.shift();
    db.集合.remove({_id: {$in: doc.dups}});
})

db.order_warning_info.aggregate([{$match:{"iotprofile" : "通用磨坊测试"}},
{
$group: { _id: {order_id: '$order_id',scan_time: '$scan_time'},count: {$sum: 1},dups: {$addToSet: '$_id'}}
},
{
$match:{count:{$gt:1}}
}
]).forEach(function(doc){
doc.dups.shift();
db.order_warning_info.remove({_id: {$in: doc.dups}});
})


#$match  后面跟插叙你的条件
#group:  后面跟去重的条件
#$addToSet   以_id存储结构