MongoDB more complex comprehensive statistical calculation, performance is not bad

Db.app_users.aggregate ([ {      $project:{          fs:1,         ls:1,          subt:{$subtract: [' $ls ', ' $fs ']},          days714:{              $cond:  [  {  $gte: [' $ls ', (Math.Round (New date ()). GetTime ()  / 1000) -14*24*60*60)]},1,0]          },          days1430:{              $cond: [              {                   $and:[                     {  $lte: [' $ls ', (Math.Round (New date ()). GetTime ()  / 1000) -14*24*60*60)]},                     {  $gte: [' $ls ', (Math.Round (New date ()). GetTime ()  / 1000) -30*24*60*60)]}                  ]             } ,1,0]         },                          days30:{               $cond: [ {  $lte: [ ' $ls ', (Math.Round ((New date ()). GetTime ()  / 1000) -30*24*60*60)]},1,0]          },                   days815:{              $cond: [              {                   $and:[                     {  $lte: [' $ls ', ( Math.Round ((New date ()). GetTime ()  / 1000) -8*24*60*60)]},                     {  $gte: [' $ls ', ( Math.Round ((New date ()). GetTime ()  / 1000) -15*24*60*60)]}                  ]              },1,0]         },          days1531:{              $cond:  [              {                   $and:[                     {  $lte: [' $ls ', ( Math.Round ((New date ()). GetTime ()  / 1000) -15*24*60*60)]},                     {  $gte: [' $ls ', ( Math.Round ((New date ()). GetTime ()  / 1000) -31*24*60*60)]}                  ]              },1,0]         },                           days31:{              $cond:  [  {  $lte: [' $ls ', (Math.Round (New date ()). GetTime ()  / 1000) -31*24*60*60)]},1,0]          },     } }, {       $match: {         subt:{$lt:24*60*60},          ls:{  $lt:(Math.Round ((New date ()). GetTime ()  /  1000) -7*24*60*60)}     } }, {      $group: {           ' _id ':null,          days7_14: {$sum: &nbsP; " $days 714 "},         days14_30: {$sum: " $days 1430 "},          days_more30: {$sum:  "$days"},          days8_15: {$sum:  "$days 715"},          days15_31: {$sum:  "$days 1531"},          days_more31: {$sum:  "$days"}     } }])

MongoDB more complex comprehensive statistical calculation, performance is not bad