mongodb copy data from one collection to another

One: Concept The popular copy set is to use multiple machines for the same data asynchronous synchronization, so that multiple machines have multiple copies of the same data, and when the main library when it is off without user intervention,

The blog has moved Https://www.tianmingxing.com MongoDB is an open-source, document-oriented NoSQL (not only SQL) database written using C + +, and one of the most popular NoSQL databases. NoSQL Introduction NoSQL means "Not just SQL", is the

If you have never been familiar with MongoDB or have a little understanding of MongoDB, if you are a C # developer, take a few minutes to read this article. This article will take you step by step to get started easily. Read directory 1:

First, the introduction of replicationThe so-called replication is the process of synchronizing data between multiple hosts.1. Data redundancy and availabilityReplication technology provides data redundancy and availability, using multiple copies of

That's not true.Collection's single doc has a size limit and is now 16MB, which makes it impossible for you to rub everything into a Collection. And if the collection structure is too complex, it will affect the efficiency of query and update, and

I. Basic concepts of replica setsReplica set (replica set)MongoDB's replica set is a Mongod process instance cluster where data is replicated to each other in the cluster and is automatically failover.MongoDB's database replication adds redundancy,

MongoDB data migration and synchronization of MONGODB data replicationMongoDB requires a minimum of two instances of replication. One is the master node master, which handles client requests and the rest is slave, which is responsible for

In order to save the user data and business data for a site, a database is usually required. MongoDB and node. JS are particularly well-matched because MongoDB is a document-based, non-relational database that is stored in Bson (the lightweight

MongoDB is one of the most widely used NoSQL (not-only SQL) engines in the world, ranking very well above the db, and is the May ranking:　　You can see that the previous four are traditional relational databases, and MongoDB is the first in NoSQL.

MongoDB is a popular NoSQL database, it is stored in the form of document-type storage, not key-value. About the characteristics of MongoDB, here is not more introduced, we can go to see the official note: http://docs.mongodb.org/manual/Today, the