AWS DynamoDb

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Arjit Sharma
02 Mins

We already have EC2 for compute and S3 for storage, so where do we store application data that needs fast access, flexible schema, and massive scalability?

Meet DynamoDB - AWS’s answer to NoSQL databases.

What Is DynamoDB?

DynamoDB is a serverless key-value and document database.

It’s ultra-fast, highly available, auto-scalable, and fully managed - meaning you never worry about servers or database maintenance.

When to Use DynamoDB:

  • Backend for mobile/web apps (user profiles, posts, likes)
  • Shopping carts, chat apps, session storage
  • IoT device data
  • Anywhere low-latency access at any scale is needed

How DynamoDB Works

  • Key-Value Store: Every item in DynamoDB is stored with a primary key (like an ID) and associated attributes.
  • Partitions: Data is split across partitions based on the primary key to achieve scale. It uses consistent hashing to save data across multiple servers based on partition key.
  • Replication: DynamoDB automatically replicates your data across multiple AZs (Availability Zones) for high durability.
  • Capacity Modes:
    • Provisioned: Manually set read/write throughput.
    • On-Demand: Pay only for what you use (recommended for unpredictable traffic).
  • SSD Storage: DynamoDB runs on fast SSD drives and uses in-memory caches (DAX) for even faster reads if needed.

Key Concepts in DynamoDB (Quick Reference)

ConceptWhat it Means
ItemA single record (like a row in SQL)
AttributeA property of an item (like a column)
TableA collection of items
Primary KeyUnique key for fetching item fast (Partition key / Partition + Sort key)
GSI (Global Secondary Index)Enables querying by alternative keys
LSI (Local Secondary Index)Allows sorting by a different attribute within the same partition

Key Concept: Partition Key vs Sort Key

  • Partition Key: Determines the partition location for the item. Must be unique if no sort key is defined.
  • Sort Key (Optional): Allows multiple items with the same partition key, sorted by this attribute.
  • Combined, they form a composite primary key which must be unique.

Up and Running with DynamoDB

Creating DynamoDB Table

  1. Go to AWS Console → DynamoDB → Create Table.
  2. Set Table Name* (e.g., Users).
  3. Set Primary Key:
    • Partition Key: A unique identifier (e.g., UserId).
    • (Optional) Sort Key: Additional way to organize data (e.g., CreatedAt).
  4. Choose on-demand capacity unless you have predictable load.
  5. Create table - ready to use!

No need to think about servers, indexes (unless you want), or backups (automatic).

Using DynamoDB with Nodejs

Step 1: Install AWS SDK

npm install aws-sdk

Step 2: Configure DynamoDB Client

const AWS = require('aws-sdk');
const dynamoDb = new AWS.DynamoDB.DocumentClient({
  region: 'us-east-1',
});

Step 3: Put Item

const params = {
  TableName: 'Users',
  Item: {
    UserId: '123',
    Name: 'Alice',
    Email: 'alice@example.com',
  },
};

dynamoDb.put(params).promise()
  .then(() => console.log('User created'))
  .catch(err => console.error(err));

Step 4: Fetch (Get Item)

const params = {
  TableName: 'Users',
  Key: {
    UserId: '123',
  },
};

dynamoDb.get(params).promise()
  .then(data => console.log(data.Item))
  .catch(err => console.error(err));

Go complete serverless

Imagine creating a serverless and scalable app with near-zero infra management

  • API Gateway for HTTP endpoints
  • Lambda for business logic
  • DynamoDB for data persistence
Frontend → API Gateway → Lambda → DynamoDB
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