When an optional key in a collection is queried , performance varied with respect to the following two queries. Good response : When it queried with a specific value - a value other than null, it resulted good response time.…
compound index: { A: 1, B: 1, C: 1 } query: col.aggregate([ { $match: { B: "ssome_value", C: "some_other_value, } } ]) The query does not involve A, so the compound index is not used. I can do this to…
compound index { A: 1, B: 1 } In this query, the compound index is not used: db.user.aggregate([ { $match: { B: { $gt: 100 } } }, { $sort: { A: 1 } }, { $limit: 1000 } ])…
Does MongoDB createIndexes() method, support specifying individual options for each index set in the script. Something like this below, which is not working by the way. Ref - https://www.mongodb.com/docs/v5.0/reference/method/db.collection.createIndexes/#mongodb-method-db.collection.createIndexes var indexes = [ { key: { "productId":1, "productName":1 }, partialFilterExpression:…
The following statement regarding range filter and sorting and the way the predicates had to be placed is confusing. "MongoDB cannot do an index sort on the results of a range filter. Place the range filter after the sort predicate…
The $lookup stage will return an array of subdocuments. But the only value that I am interested in from the result of the $lookup is the the _id value. So instead of an array of { _id: ObjectId() }, how…
Let's say I have this document: { "_id": objectId(), "products": [ { "product_id": "" } ] } I would like to make that the key product_id of documents in the array products must be unique for that document in the…
{ name: "use_name", grades: [ {class: "math": grade: 100}, {class: "english": grade: 90} ] } How do I write an aggregation pipeline to output: { name: "use_name", grades: {class: "math": grade: 100}, } The grades field has been reduced to…
I have a MongoDB(v 5.0.6) collection with the following data: [{ "_id": { "$oid": "63bc06e6aa310000d6004a68" }, "key": "title", "label": "title", "type": "text", "searchable": 0 },{ "_id": { "$oid": "63bc06e6aa310000d6004a69" }, "key": "attribution", "label": "attribution", "type": "text", "searchable": 0 },{ "_id":…
Does it make any sense at all, since the each value of the prefix will have only one value of any suffix, there is no further sorting that can be done after the prefix?