aggregation-framework

问题 we are trying to create call to MangoDB to receive all possible filters for products. I will try to create example of our products First product is Adidas Shoes which have two options to select - colour and size. But for different colours you have different sizes. { id: 1 name: "Adidas Shoes", filters: [ [ { code: "brand", value: "Adidas" }, { code: "colour", value: "white" }, { code: "size", value: 41 } ], [ { code: "brand", value: "Adidas" }, { code: "colour", value: "white" }, { code:

问题 With a collection of documents with fields field1 , field2 , field3 and so on, I need to find distinct values for field3 for each distinct value of field3 , need to get the first document with each distinct value in field3 For # 1, I could do db.myCollection.distinct("field3") How do I go about #2 ? Sample Collection: [ { "field1": 11, "field2": "toyota", "field3": "camry" }, { "field1": 22, "field2": "toyota", "field3": "corolla" }, { "field1": 33, "field2": "toyota", "field3": "camry" }, {

问题 I have a multiple collections , I used the separate collection & foreign key approach , and I want to join this collections to build a nested collections. this is my schemas of collections: const SurveySchema = new Schema({ _id:{ type: Schema.ObjectId, auto: true }, name: String, enabled: {type: Boolean, Default: true}, created_date:{type: Date, Default: Date.now}, company: {type: Schema.Types.ObjectId, ref: 'Company'},}); const GroupSchema = new Schema({ _id:{ type: Schema.ObjectId, auto:

问题 I find out the aggregate framework, but how to get the doucments in a month or a week? I am tring to calculate how many orders are placed in a week or in a month. The documents are like this: { "_id" : ObjectId("53834167b54a3b22f0079e2c"), "createdDate" : ISODate("2014-05-26T13:28:07.942Z"), "__v" : 0 }, { "_id" : ObjectId("53834167b54a3b22f0079e2c"), "createdDate" : ISODate("2014-05-28T09:28:07.942Z"), "__v" : 0 } All I want to have is how many orders are placed in a month according the

问题 MongoDB: how to do something like this, both in mongo console and via JavaScript, Node.js: db.turnys.find( { users:{$size:seats } } ) turnydb.turnys looks like this: [ { "gId": "5335e4a7b8cf51bcd054b423", "seats": 2, "start": "2014-03-30T14:23:29.688Z", "end": "2014-03-30T14:25:29.688Z", "rMin": 800, "rMax": 900, "users": [], "_id": "533828e1d1a483b7fd8a707a" }, { "gId": "5335e4a7b8cf51bcd054b423", "seats": 2, "start": "2014-03-30T14:23:29.688Z", "end": "2014-03-30T14:25:29.688Z", "rMin": 900

问题 i am trying to toggle a boolean value inside a object, which is a subdocument, i am having hard time to update a particular object within an array. Document: "_id" : ObjectId("54afaabd88694dc019d3b628") "Invitation" : [ { "__v" : 0, "ID" : ObjectId("54af6ce091324fd00f97a15f"), "__t" : "USER", "_id" : ObjectId("54b4ceb50fc380001bea1752"), "Accepted" : false }, { "__v" : 0, "ID" : ObjectId("54afac5412f5fdcc007a5c4d"), "__t" : "USER", "_id" : ObjectId("54b4cebe0fc380001bea1753"), "Accepted" :

问题 I have a collection with below data structure: [{name: "123", category: "A"}, {name: "456", category: "B"}, {name: "789", category: "A"}, {name: "101", category: "C"}] I want to be able to sort them according to the value of category , by specifying which comes first. For example, sorting the query in the order of B->C->A, the result would yield: [{name: "456", category: "B"}, {name: "101", category: "C"}, {name: "123", category: "A"}, {name: "789", category: "A"}] Is there any good way of

问题 I'm trying to use a mongodb aggregation query to join($lookup) two collections and then distinct count all the unique values in the joined array. *Note: I don't necessarily know what fields(keys) are in the metaDataMap array. And I don't want to count or include fields that might or might not exist in the Map. So that's why the aggregation query looks like it does. So my two collections look like this: events- { "_id" : "1", "name" : "event1", "objectsIds" : [ "1", "2", "3" ], } Objects { "

问题 Forgive me if I confuse some terminology here, but I'm performing a join operation in an aggregation using the '$lookup' operator as shown here: db.collection('items').aggregate([{$match: {}}, { $lookup: { from: 'usr', localField: 'usr._id', foreignField: '_id', as: '__usr' } }, { $project: { info: 1, timestamp: 1, usr: { "$arrayElemAt": [ "$__usr", 0 ] } } }], (err, result) => { res.json(result); db.close(); }); I'm performing a projection on the aggregation result, and I'm using '

问题 Based on the aggregation pipeline docs, "any single aggregation operation consumes more than 10 percent of system RAM, the operation will produce an error." - http://docs.mongodb.org/manual/core/aggregation-pipeline-limits/ Is there any way of increasing this limit? I have also set allowDiskUse: true (so the error is no longer an issue), but would like to use more RAM to improve performance. Background: I am running a large aggregate job on mongodb on about 100 million entries. It is