Mongodb批量删除gridfs文件实例

差不多1个多小时后over， 舒坦了，100G空间啊！！！

Be aware that this command can take a long time to run if your database is large. In addition, it requires a quantity of free disk space equal to the size of your database. If you lack sufficient free space on the same volume, you can mount a separate volume and use that for the repair. In this case, you must run the command line and use the –repairpath switch to specify the folder in which to store the temporary repair files. Warning：This command obtains a global write lock and will block other operations until it has completed.