原表記錄:
需要把related_type=1 and action_type=3 並且related_id相同的刪掉一條。只留一個去重。
db.user_action_log.aggregate([
{$match:{related_type:1,action_type:3}}, (查詢條件)
{
$group: { _id: {related_id: '$related_id'},count: {$sum: 1},dups: {$addToSet: '$_id'}} (根據related_id分組,$group只會返回參與分組的字段,使用$addToSet在返回結果數組中增加_id字段)
},
{
$match: {count: {$gt: 1}} (匹配數量大於1的數據)
}
]).forEach(function(doc){ (使用forEach循環根據_id刪除數據)
doc.dups.shift();
db.user_action_log.remove({_id: {$in: doc.dups}});
})
刪除後數據:
db.user_action_log.aggregate([
{$match:{related_type:1,action_type:3}},
{
$group: { _id: {related_id: '$related_id'},count: {$sum: 1},dups: {$addToSet: '$_id'}}
},
{
$match: {count: {$gt: 1}}
}
]).forEach(function(doc){
doc.dups.shift();
db.user_action_log.remove({_id: {$in: doc.dups}});
})