MongoDB: Next Steps Live Demos

docker_compose.yaml

version: "2"
services:
  mongo-shard1:
    image: mongo
    command: mongod --shardsvr --replSet mongors1 --dbpath /data/db --port 27017
  mongo-shard2:
    image: mongo
    command: mongod --shardsvr --replSet mongors2 --dbpath /data/db --port 27017
  mongo-cfg1:
    image: mongo
    container_name: mongocfg1
    command: mongod --configsvr --replSet mongoconf --dbpath /data/db --port 27017
  mongo-cfg2:
    image: mongo
    container_name: mongocfg2
    command: mongod --configsvr --replSet mongoconf --dbpath /data/db --port 27017
  mongos:
    container_name: mongos
    image: mongo
    depends_on: 
      - mongo-cfg1
      - mongo-cfg2
    command: mongos --configdb mongoconf/mongocfg1:27017,mongocfg2:27017 --port 27017
    ports: 
      - 27019:27017
    expose:
      - 27017

gistfile1.txt

Live Demo contents and commands for MongoDB: Next Steps

replica_sets.js

// Attach container
docker exec -it mongo /bin/bash

// Create data directories since the main mongod is using /data/db

mkdir -p /tmp/db{1,2,3}

// Run mongod processes for RS
mongod --replSet nextSteps --port 27000 --dbpath /tmp/db1 --oplogSize 200
mongod --replSet nextSteps --port 27001 --dbpath /tmp/db2 --oplogSize 200
mongod --replSet nextSteps --port 27002 --dbpath /tmp/db3 --oplogSize 200

// Connect to a mongod process via a shell
mongo --port 27000

// Inside the shell
rsconf = {
    _id: "nextSteps",
    members: [
      {_id: 0, host: "localhost:27000"},
      {_id: 1, host: "localhost:27001"},
      {_id: 2, host: "localhost:27002"} 
    ]
  }
rs.initiate(rsconf)
db.isMaster()
rs.status()

use oreilly

for (i=0; i<200; i++) {db.testing.insert({_id: i})}

db.testing.findOne()

// Go to a secondary, let's say (is random sop choose your own) 27002

secondaryConn = new Mongo("localhost:27002")
secondaryDB = secondaryConn.getDB("oreilly")
secondaryDB.testing.find() //errors

secondaryConn.setSecondaryOk()

secondaryDB.testing.find() // success

secondaryDB.testing.insert({"_id" : 201}) // not master!

db.adminCommand({"shutdown" : 1})

secondaryDB.isMaster() // primary changed!!

sharding.js

// Start config server

docker-compose up

docker exec -it mongo-cfg1 /bin/bash

mongo

// Inside the shell
rsconf = {
    _id: "mongoconf",
    members: [
      {_id: 0, host: "mongocfg1:27017"},
      {_id: 1, host: "mongocfg2:27017"},
    ]
  }
rs.initiate(rsconf)
rs.status()

mongo --host mongo-shard1

rsconf = {
  _id: "mongors1",
  members: [
    {_id: 0, host: "mongo-shard1:27017"},
  ]
}
rs.initiate(rsconf)
rs.status()

mongo --host mongo-shard2

rsconf = {
  _id: "mongors2",
  members: [
    {_id: 0, host: "mongo-shard2:27017"},
  ]
}
rs.initiate(rsconf)
rs.status()

docker exec -it mongos /bin/bash
mongos
use admin
sh.addShard("mongors1/mongo-shard1:27017" )
sh.addShard("mongors2/mongo-shard2:27017" )
sh.status()

sh.enableSharding("oreilly")
db.test.createIndex({ "age" : "hashed" })
sh.shardCollection("oreilly.test", {"age":"hashed"}, false, { numInitialChunks: 10 })

function getRandomInt(min, max) {
  min = Math.ceil(min);
  max = Math.floor(max);
  return Math.floor(Math.random() * (max - min + 1)) + min;
}

for (i=0; i<1000; i++) {db.test.insert({age: getRandomInt(0,95), grade: getRandomInt(1,10)})}

sh.status()

db.test.explain().find()