Get execution stats in MongoDB for a collection


To get stats, use explain() in MongoDB. Let us create a collection with documents −

> db.demo157.insertOne({"Status":"Active"});
{
   "acknowledged" : true,
   "insertedId" : ObjectId("5e354fdffdf09dd6d08539fc")
}
> db.demo157.insertOne({"Status":"InActive"});
{
   "acknowledged" : true,
   "insertedId" : ObjectId("5e354fe3fdf09dd6d08539fd")
}

Display all documents from a collection with the help of find() method −

> db.demo157.find();

This will produce the following output −

{ "_id" : ObjectId("5e354fdffdf09dd6d08539fc"), "Status" : "Active" }
{ "_id" : ObjectId("5e354fe3fdf09dd6d08539fd"), "Status" : "InActive" }

Following is how to implement explain() in MongoDB −

> db.demo157.find({Status: { $in: ['Active','InActive'] }}).explain("executionStats");

This will produce the following output −

{
   "queryPlanner" : {
      "plannerVersion" : 1,
      "namespace" : "test.demo157",
      "indexFilterSet" : false,
      "parsedQuery" : {
         "Status" : {
            "$in" : [
               "Active",
               "InActive"
            ]
         }
      },
      "winningPlan" : {
         "stage" : "COLLSCAN",
         "filter" : {
            "Status" : {
               "$in" : [
                  "Active",
                  "InActive"
               ]
            }
         },
         "direction" : "forward"
      },
      "rejectedPlans" : [ ]
   },
   "executionStats" : {
      "executionSuccess" : true,
      "nReturned" : 2,
      "executionTimeMillis" : 18,
      "totalKeysExamined" : 0,
      "totalDocsExamined" : 2,
      "executionStages" : {
         "stage" : "COLLSCAN",
         "filter" : {
            "Status" : {
               "$in" : [
                  "Active",
                  "InActive"
               ]
            }
         },
         "nReturned" : 2,
         "executionTimeMillisEstimate" : 0,
         "works" : 4,
         "advanced" : 2,
         "needTime" : 1,
         "needYield" : 0,
         "saveState" : 0,
         "restoreState" : 0,
         "isEOF" : 1,
         "invalidates" : 0,
         "direction" : "forward",
         "docsExamined" : 2
      }
   },
   "serverInfo" : {
      "host" : "DESKTOP-QN2RB3H",
      "port" : 27017,
      "version" : "4.0.5",
      "gitVersion"
      "3739429dd92b92d1b0ab120911a23d50bf03c412"
   },
   "ok" : 1
}

Updated on: 01-Apr-2020

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