MongoDB (Replica set)

A replica set is a cluster configuration method under MONGO:

1, the main node data is synchronized to the replica node by Oplog, Oplog does not log the query statement (because it does not change the data);

2, MONGO replica set can have a master node, multiple replica nodes, the master node is automatically elected;

This article describes a basic replica cluster in a stand-alone configuration, operating system Windows7,mongodb version 2.6.4

1. Create master node, replica node database folder master/db and replset/db

2. Start the database instance of the master node and replica node as follows:

Mongod.exe--dbpath. /master/db--port 10000--replset REPL

Mongod.exe--dbpath. /replset/db--port 20000--replset repl

3, arbitrary landing a node, configuration copy

Mongo.exe localhost:10000

Use admin

Config = {_id: "Repl", Members:[{_id:0,host: "localhost:10000"},{_id:1,host: "localhost:20000"}]}

Rs.initiate (config);//Configure replica set

After the configuration is successful, the Rs.status () command can be queried with the following feedback:

That is, 20000 port is the main point, 10000 port is the replica node

4. Testing

We log in to the master node for data writing:

Go to query from node:

Note: You must turn on Read permissions from the node, as follows

We can find the Oplog record in the local database of the node:

MongoDB (Replica set)