Mongo is great. I'm using it in more then one project, and I love it.
Is there a real reason to switch to Dynamo db? Well, there are few:
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Mongo is a memory hog. This means you have to maintain pretty big instances in order to keep it fast and happy.
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Servers cost money. Not only the hourly fee, but maintenance as well. The lean startup couldn't probably afford these, and bigger companies might want the easy scalability that comes with Dynamo. Scaling Mongo is not hard, but it’s yet another thing to do.
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Serverless. Using Node JS and Serverless, allows you to run a whole infrastructure without… well… an infrastructure. This is huge as you don’t have to maintain anything.
So, how do we migrate?
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Indexes. While Mongo enforces record ID, Dynamo enforces at least one index, with the option of another one. Migration here is pretty easy: create the main index as string, and add a random string to it upon inserting a new record:
function createUsersTable(callback) { let params = { TableName: TABLE_NAME, KeySchema: [{ AttributeName: "user_id", KeyType: "HASH" }, ], AttributeDefinitions: [{ AttributeName: "user_id", AttributeType: "S" }], ProvisionedThroughput: { "ReadCapacityUnits": 5, "WriteCapacityUnits": 5 } } dynamodb.createTable(params, (err, data) => { callback(err, data) }); } -
Dynamo is able to offer a schema of some sort. You don’t have to use it, but if you can, you can guarantee a certain consistency within the records.
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Dynamo requires types when storing data. But, If you’re using NodeJS, you’re in luck. AWS.DynamoDB.DocumentClient will extract these for you, resulting in an extremely similar manner to what you know and love from mongo:
let dynamo = new AWS.DynamoDB.DocumentClient
and inserting a record is as easy:
function addUser(callback) { let params = { TableName: TABLE_NAME }; let item = { user_id: rand.generate(), username: "Bick "+rand.generate(7), password: rand.generate(10), address: { home: "123 wrefwre,fwref", work: "wre 5whbwergwregwerg" } } params.Item = item; dynamo.put(params, callback); }Where rand is a module I've used to generate random strings (see full source link at the bottom).
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Running locally: Using Mongo locally is easy. it’s open source, and you can just install it. Dynamo DB is proprietary software, and you can’t get a copy of it. Amazon solved it by creating a Java version of the api backed by sqlite. You can now run a front of Dynamo db if you need to test your code. The only setup you need to do is the aws config:
const credentials = { accessKeyId: "fakeAccessKey", secretAccessKey: "fakeSecretAccessKey", region: "fakeRegion", endpoint: "http://localhost:15000" };
For the local version of Dynamo db installing instructions: https://github.com/talreg/dynamodb-node/blob/master/README.md
The full sample project can be found here: https://github.com/talreg/dynamodb-node