nosql

问题 just wondering if anyone can come up with a smarter way to do this... Let's say I have some documents in MongoDB with a version property, for example something like { ..., version: { major: 1, minor: 2, patch: 13 } } , or { ..., version: "1.2.13" } if it is easier. What's the easiest way to find all documents that have version X.Y.Z or above? The way I'm doing it now is basically a huge $and clause. 回答1: Your first design is actually very good. The reason is because you can index the fields

问题 So, I want to create a client side based paritioning schema, where I set the collection name as function(), my pseudo code is something like that: var mongoose = require('mongoose'), Schema = mongoose.Schema, var ConvForUserSchema = new Schema({ user_id: Number, conv_hash: String, archived: Boolean, unread: Boolean }, function CollectionName() { return (this.user_id % 10000); }); Is this in any way possible through moongose such that both read and writes will work as expected? 回答1: Hello you

问题 I have interfaces extends from MongoRepository. They are using default database of mongodb. I would like to define the database name for the classes. public interface CustomerRepository extends MongoRepository<Customer, String> { ... } How can I define it? 回答1: You just need to define respective mongobd properties in application.properties file or if you want to yml syntax then define props in application.yml . Under src/main/resources , application.properties should be there already.

问题 I have interfaces extends from MongoRepository. They are using default database of mongodb. I would like to define the database name for the classes. public interface CustomerRepository extends MongoRepository<Customer, String> { ... } How can I define it? 回答1: You just need to define respective mongobd properties in application.properties file or if you want to yml syntax then define props in application.yml . Under src/main/resources , application.properties should be there already.

问题 I've been trying to make replay system. So basically when player moves, system saves his datas(movements, location, animation etc.) into JSON file. In the end of the record, JSON file may be over 50 MB . I'd want to save this data into Redis with expire date (24-48 hours). My questions are; Is it bad to save over 50 MB into Redis with expire date? How many datas that over 50 MB can Redis handle without performance loss? If players make 500 records in 48 hours, may it be bad for Redis? How

问题 Using relational db as an example, given two tables like below, where when rows in tableA and tableB have the same values, they represent the same "thing" but in different "state". So for ID=1, this thing has gone through stage1 and 2. But for ID=2, this thing has only gone through stage1. tableA (Id, columnA, columnB) 1, "a", "b" 2, "x", "y" 3, "z", "a" tableB (Id, columnA, columnB) 1, "e", "f" I want to find all the rows from tableA that don't exist in tableB . select a.* from tableA a left

问题 Using relational db as an example, given two tables like below, where when rows in tableA and tableB have the same values, they represent the same "thing" but in different "state". So for ID=1, this thing has gone through stage1 and 2. But for ID=2, this thing has only gone through stage1. tableA (Id, columnA, columnB) 1, "a", "b" 2, "x", "y" 3, "z", "a" tableB (Id, columnA, columnB) 1, "e", "f" I want to find all the rows from tableA that don't exist in tableB . select a.* from tableA a left

问题 How can I find the document id that was just updated using the updateOne -post hook in Mongoose? It might look something like this: schema.post("updateOne", function (val) { if(val.nModified > 0) { /// "this" here refers to the schema, not the document... /// How can I get the _id field of the document that was modified? } } Currently for the updateOne -post hook in Mongoose, this refers to the query, not to the document itself being modified. See here: https://mongoosejs.com/docs/middleware

问题 I have a "chat" mongoose Schema which has the following properties: const schema = mongoose.Schema({ ... recipient: { type: mongoose.Types.ObjectId, required: true, ref: 'User', }, sender: { type: mongoose.Types.ObjectId, required: true, ref: 'User', }, content: { type: String, }, ... }, { timestamps: true, }); Generally, I want to fetch the last message of each coversation that a user has. Meaning that I need to provide a user id (that can be either stored in the sender or recipient field)

问题 I have a collection of tasks on my Firestore database like this: "tasks": { v8NC4GovVOPe21fhwtp0 : { id: "v8NC4GovVOPe21fhwtp0" status: 0 dateFrom: 30 april 2019 at 00:00:00 UTC-3 dateTo: 05 may 2019 at 00:00:00 UTC-3 .... }, v7NC4GaxVOPe48ftstp1 : { id:"v7NC4GaxVOPe48ftstp1" status: 0 dateFrom: 29 april 2019 at 00:00:00 UTC-3 dateTo: 02 may 2019 at 00:00:00 UTC-3 .... } } The document has a dateFrom field, which indicates the first date the user can start working on that task and an dateTo