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First: A brief introduction to MonoDB MongoDB is a database between relational database and non-relational database. It is written in C++ language. Its advantage is that the query format supported by MongoDB is very powerful. It can store complex data types and support indexing.   Two: Download Official address: https://www.mongodb.com/ Do ...

Looking at the source code of the previous blog again, I found I couldn't understand even myself.Think about returning to the OOP line mode in order to make time for delivery. Look at this code: (post & parameters('pid,'desc.?,'width.as[Int].?,'heigth.as[Int].?)) { (pid, optDesc, optWid, optHgh) => val futCount: Fut ...

Links to the original text: https://www.jianshu.com/u/8f2987e2f9fb Although scrapy can do a lot of things, it is hard to achieve large-scale distributed applications. A capable person changes the queue scheduling of scrapy, separates the sta ...

MongoDB Learning Notes (3) - Mongo Shell Common Query Command The version of MongoDB used in this article is 4.0.10 > db.version(); 4.0.10 1. find command for brief query Find (query condition, field returned) 1. Return all fields when querying Db. user. find () - > Query all data in the user collection > db.user.find() { "_id" : Obj ...

1 mongoDB replica set Introduction to 1 replica set We introduced the use of single-machine MongoDB. In practice, we seldom use single-machine MongoDB, because there is a risk of data loss when using single-machine, and single-server can not achieve high availability (that is, when the server goes down, there is no substitute for the top of t ...

This paper mainly introduces the method of backup and recovery of MongoDB replica set, common commands, and some specific operation procedures. Finally, a backup scheme is introduced. I. Backup Method 0,oplog 0.1 What is oplogoplog is a capped collection, located in the local library 0.2 local Librarylocal libraries are the system libraries of ...

Learning excerpt from MongoDB Authoritative Guide Insert Use insert method This action document automatically generates a'_id'key >db.foo.insert({"bar" : "baz"}) Batch insert, using batchInsert function >db.foo.batchInsert([{ "_id" : 0 } , { "_id" : 1 } , { "_id" : 2 }]) The maximum message length currently acceptable to mongodb is 48MB, ...

Mongo Document Database (Bson = JSON binarization on Gridfs disks) Features: The internal execution engine is a JS interpreter. Documents are stored in a bson structure. When querying, they are converted into json objects and can be manipulated by familiarizing themselves with JS grammar. 2. The biggest difference between mongo and tradi ...

In January 2017, due to the negligence of the configuration of most mongodb, a series of cups and utensils happened. The so-called configuration negligence is that the owner of mongdb does not open authorization authentication for mongodb, resulting in the database "in any network environment, do not use account direct login". This t ...

MongoDB is a product between relational database and non-relational database, which has the most abundant functions and resembles relational database. It aims to provide a scalable and high-performance data storage solution for WEB applications. It supports a very loose data structure, is similar to JSON BSON format, so it can store more comple ...