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How would you troubleshoot locking issues in MongoDB? |
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Answer» The $GRAPHLOOKUP LOOKS like this for a query from the EMPLOYEES collection where “manager” is the self-referencing field db.employees.aggregate( [ { $graphLookup: { from: "employees", startWith: "DAVID", connectFromField: "manager", connectToField: "name", as: "REPORTING Structure" } } ] )The value of as, which is “Reporting Structure” in this case is the name of the array field which contains the documents traversed in the $graphLookup to reach the output document. For the following documents in the employee collection, { "_id" : 4, "name" : " David " , "manager" : "Sarah" } { "_id" : 5, "name" : "John" , "manager" : "David" } { "_id" : 6, "name" : "Richard", "manager" : " John " } { "_id" : 7, "name" : "Stacy" , "manager" : " Richard " }“Reporting Structure” for each output document would look like this { "_id" : 5, "name" : "John" , "manager" : "David", "Reporting Structure" : [] } { "_id" : 6, "name" : "Richard", "manager" : " John ", "Reporting Structure" : [{ "_id" : 5, "name" : "John" , "manager" : "David" }] } { "_id" : 7, "name" : "Stacy" , "manager" : " Richard", "Reporting Structure" : [{ "_id" : 5, "name" : "John", "manager" : "David" } { "_id" : 6, "name" : "Richard", "manager" : " John " }] } |
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