mongodb - 超出 $group 的記憶體限制

Question

超出了 $group 的記憶體限制，但不允許外部排序。透過allowDiskUse:true 選擇加入

雷雷

Answer 1

$group有記憶體限制你的資料量超過了限製而且沒有指定允許使用額外的磁碟進行操作於是就報錯了
The $group stage has a limit of 100 megabytes of RAM. By default, if the stage exceeds this limit , $group will produce an error. However, to allow for the handling of large datasets, set the allowDiskUse option to true to enable $group operations to write to temporary files.See db.collection.aggregate() method details.