Steps to Implement Horizontal Scaling in MongoDB
Step 1: Set Up the Environment
Before starting, ensure you have multiple servers available to act as shards, config servers, and query routers.
Step 2: Install MongoDB
Install MongoDB on all servers that will act as shards, config servers, and query routers.
Step 3: Configure Shards
Start each MongoDB instance that will be a shard with the appropriate configuration. For example:
mongod --shardsvr --port 27018 --dbpath /data/shard1 --logpath /var/log/mongodb/shard1.log --fork
Repeat the process for all shard servers, ensuring each one is configured correctly.
Step 4: Configure Config Servers
Start the config servers with the appropriate configuration:
mongod --configsvr --port 27019 --dbpath /data/config --logpath /var/log/mongodb/config.log --fork
Repeat the process for all config servers.
Step 5: Start the Query Routers (Mongos)
Start the Mongos instances to act as query routers:
mongos --configdb configReplSet/localhost:27019,localhost:27020,
localhost:27021 --logpath /var/log/mongodb/mongos.log --fork
Ensure the configDB setting correctly points to the config servers.
Step 6: Connect to the Mongos
Connect to the mongos instance using the MongoDB shell:
mongo --port 27017
Step 7: Add Shards to the Cluster
Within the MongoDB shell, add each shard to the cluster:
sh.addShard("shard1/localhost:27018")
sh.addShard("shard2/localhost:27019")
sh.addShard("shard3/localhost:27020")
Step 8: Enable Sharding for a Database
Enable sharding for a specific database:
sh.enableSharding("myDatabase")
Step 9: Shard a Collection
Shard a collection within the database by specifying a shard key:
sh.shardCollection("myDatabase.myCollection", { shardKey: 1 })
How to Perform Horizontal Scaling in MongoDB?
Horizontal scaling, also known as scaling out, involves adding more servers to a database system to handle increased load. In the context of MongoDB, horizontal scaling is implemented through a process called sharding. This article will delve into the details of horizontal scaling in MongoDB, discussing what it is, how it works, and the steps to set it up.