mongodb-.net-driver

问题 I am currently developing a document store in Mongo DB which contains a complete material breakdown of a specific item. The breakdown is calculated and contains a composite structure. The domain model: public interface IReagent { int ItemId { get; set; } int Quantity { get; set; } ConcurrentBag<IReagent> Reagents { get; set; } } public class Craft : IReagent { public int ItemId { get; set; } public int Quantity { get; set; } public int SpellId { get; set; } public int Skill { get; set; }

问题 I am moving our messaging system to MongoDB and am curious what approach to take with respect to various stats, like number of messages per user etc. In MS SQL database I have a table where I have different counts per user and they get updated by trigger on corresponding tables, so I can for example know how many unread messages UserA has without calling an expensive SELECT Count(*) operation. Is count function in MongoDB also expensive? I started reading about map/reduce but my site is high

问题 i am new to mongodb and stack overflow. I want to know why on mongodb collection ID is of 24 hex characters? what is importance of that? 回答1: Why is the default _id a 24 character hex string? The default unique identifier generated as the primary key ( _id ) for a MongoDB document is an ObjectId. This is a 12 byte binary value which is often represented as a 24 character hex string, and one of the standard field types supported by the MongoDB BSON specification. The 12 bytes of an ObjectId

问题 I'm exploring Mongo as an alternative to relational databases but I'm running into a problem with the concept of schemaless collections. In theory it sounds great, but as soon as you tie a model to a collection, the model becomes your defacto schema. You can no longer just add or remove fields from your model and expect it to continue to work. I see the same problems here managing changes as you have with a relational database in that you need some sort of script to migrate from one version

问题 I'm exploring Mongo as an alternative to relational databases but I'm running into a problem with the concept of schemaless collections. In theory it sounds great, but as soon as you tie a model to a collection, the model becomes your defacto schema. You can no longer just add or remove fields from your model and expect it to continue to work. I see the same problems here managing changes as you have with a relational database in that you need some sort of script to migrate from one version

问题 I'm exploring Mongo as an alternative to relational databases but I'm running into a problem with the concept of schemaless collections. In theory it sounds great, but as soon as you tie a model to a collection, the model becomes your defacto schema. You can no longer just add or remove fields from your model and expect it to continue to work. I see the same problems here managing changes as you have with a relational database in that you need some sort of script to migrate from one version

问题 I tested two scenarios Single Huge collection vs Multiple Small Collections and found huge difference in performance while querying. Here is what I did. Case 1: I created a product collection containing 10 million records for 10 different types of product, and in this exactly 1 million records for each product type, and I created index on ProductType. When I ran a sample query with condition ProductType=1 and ProductPrice>100 and limit(10) to return 10 records of ProductType=1 and whose price

问题 I tested two scenarios Single Huge collection vs Multiple Small Collections and found huge difference in performance while querying. Here is what I did. Case 1: I created a product collection containing 10 million records for 10 different types of product, and in this exactly 1 million records for each product type, and I created index on ProductType. When I ran a sample query with condition ProductType=1 and ProductPrice>100 and limit(10) to return 10 records of ProductType=1 and whose price

问题 What is a proper way to duplicate a collection in Mongodb on the same server using C#? MongoVUE has an option 'Duplicate collection', is there something similar for C#? 回答1: There isn't a built-in way to copy collections with the C# driver, but you can still do it pretty simply as: var source = db.GetCollection("test"); var dest = db.GetCollection("testcopy"); dest.InsertBatch(source.FindAll()); Note, however, that this won't copy any indexes from the source collection. The shell's copyTo

问题 I have objects with 3 string fields Country, Province, City. They can contain null or some string name. I wanna query all data with the exact same values. For Example i need all data where City = null, Province = "WA", Country = "USA" I created BsonDocument: var lookup = new QueryDocument { {"GeoPosition.City", userLocation.City}, {"GeoPosition.Province", userLocation.Province}, {"GeoPosition.Country", userLocation.Country} }; But null field was thrown away and document looks like: {