mongodb-query

问题 I using C# driver to use MongoDb in small projects, and now I stuck with updating documents. trying to figure out how to update the field AVG (int) here is my code: IMongoCollection<Student> studentCollection = db.GetCollection<Student>("studentV1"); Student updatedStudent = new Student() { AVG = 100, FirstName = "Shmulik" }); studentCollection.UpdateOne( o=>o.FirstName == student.FirstName, **<What should I write here?>**); there is simple and clean way to update specific field(s) like the

问题 I fired a query and tried to explain it on mongo console and got "isMultiKey" : true, "n" : 8, "nscannedObjects" : 17272, "nscanned" : 17272, "nscannedObjectsAllPlans" : 21836, "nscannedAllPlans" : 21836, "scanAndOrder" : true, "indexOnly" : false, "nYields" : 0, "nChunkSkips" : 0, "millis" : 184, Most of the things are explained in http://www.mongodb.org/display/DOCS/Explain, but I cannot understand what does nscannedObjectsAllPlans, nscannedAllPlans means. Can anyone help? Thanks 回答1:

问题 Suppose I have documents like this { "id" : "1415166669", "color" : { "14" : "Silver" }, "name":"Random Name" } where the key inside color can change, i.e Next Document may look like this { "id" : "1415126969", "color" : { "11" : "Gold" }, "name":"Random Name 2" } I want to flatten and rename them so that my documents have a similar structure as follows: { "id" : "1415126969", "color" : "Gold" "name":"Random Name 2" } and { "id" : "1415166669", "color" : "Silver" "name":"Random Name" } I

问题 I have Mongo database with 16 collections. All collection has the common field domain_id . How can I remove documents with specified domain_id from all collections. I know only how to remove document from single collection. db.getCollection('collectionName1').remove({domain_id : '123'}) 回答1: Use the method db.getCollectionNames() to get a list of all the collections in your database, iterate the list using the JavaScript's forEach() method to remove the document from each collection: db

问题 Say I have the following Collections public @Data class Customer { @Id private String id; private String firstName; private String lastName; @DBRef private List<Address> addressList= new ArrayList<Address>(); } and public @Data class Address { @Id private String id; private String address; private String type; private String customerID; } And each Customer has multiple addresses, and I have implemented MongoRepository . Saving customer for the First time is working pretty well customerRepo

问题 Having this document structure (omitting irrelevant fields for brevity): [ { "_id" : 0, "partn" : [ { "date" : ISODate("2015-07-28T00:59:14.963Z"), "is_partner" : true }, { "date" : ISODate("2015-07-28T01:00:32.771Z"), "is_partner" : false }, { "date" : ISODate("2015-07-28T01:15:29.916Z"), "is_partner" : true }, { "date" : ISODate("2015-08-05T13:48:07.035Z"), "is_partner" : false }, { "date" : ISODate("2015-08-05T13:50:56.482Z"), "is_partner" : true } ] }, { "_id" : 149, "partn" : [ { "date"

问题 I have a large mongoDB database set up and am trying to create a website where a user can use a searchbar to query the database remotely and have the results posted on the site (strictly read-only). I have experience with databases for data analysis, but have never created a website for querying results. I'm don't have any experience with web development and don't know what platforms (PHP? node.js?) to use. Thanks in advance. 回答1: There are the following steps to the problem: Create the front

问题 I have a large mongoDB database set up and am trying to create a website where a user can use a searchbar to query the database remotely and have the results posted on the site (strictly read-only). I have experience with databases for data analysis, but have never created a website for querying results. I'm don't have any experience with web development and don't know what platforms (PHP? node.js?) to use. Thanks in advance. 回答1: There are the following steps to the problem: Create the front

问题 Problem I need to speedup this kind of query: db.col.find({ a: "foobar", b: { $exists: true} }); Data Distribution Existence of fields: The field a exists in all documents, The field b exists only in ~10% of them. Current Table Stats: db.col.count() // 1,050,505 db.col.count({ a : "foobar" }) // 517.967 db.col.count({ a : "foobar", b : { $exists: true} }) // 44.922 db.col.count({ b : { $exists: true} }) // 88.981 Futrue data growth: So far two batches where loaded (2x around 500,000). Each

问题 I am using the following example to better explain my need. I have a set of points(users) on a map and collection schema is as below { location:{ latlong:[long,lat] }, maxDistance:Number } i have another collection with events happening in the area. schema is given below { eventLocation:{ latlong:[long,lat] } } now users can add their location and the maximum distance they want to travel for to attend an event and save it. whenever a new event is posted , all the users satisfying their