Getting Started

Amazon DynamoDB Introduction

Learn DynamoDB — Amazon's fully managed, serverless NoSQL database that scales to any workload with single-digit millisecond performance.

What is Amazon DynamoDB?

Amazon DynamoDB is a fully managed, serverless NoSQL database service provided by AWS. You don't provision servers, manage OS patches, or worry about scaling — AWS handles all of it. You pay for the reads and writes your application performs, not for idle capacity.

DynamoDB was built at Amazon to solve an internal problem: during peak shopping events like Prime Day, they needed a database that could scale to millions of requests per second with predictable, single-digit millisecond latency — regardless of scale. That system became DynamoDB, launched publicly in 2012.

DynamoDB's Core Properties

Fully serverless — No servers to manage. Capacity scales automatically.

Predictable performance at any scale — Whether your table has 1 row or 1 trillion rows, DynamoDB delivers consistent single-digit millisecond reads and writes.

Global replication — DynamoDB Global Tables replicate your data across multiple AWS regions automatically, with active-active writes.

Built-in high availability — DynamoDB automatically replicates data across three availability zones within a region.

Two capacity modes:

On-Demand — Pay per request. Scales instantly. No capacity planning.
Provisioned — Pre-specify read/write capacity. Cheaper for predictable workloads.

DynamoDB vs. Other Databases

Feature	DynamoDB	MongoDB Atlas	PostgreSQL
Hosting	AWS-only managed	Multi-cloud	Self-hosted or managed
Scaling	Serverless, automatic	Manual or auto-scaling	Vertical / read replicas
Query model	Key-based, limited	Flexible queries	Full SQL
Consistency	Eventual or strong	Configurable	ACID
Best for	AWS-native, unpredictable scale	Flexible document queries	Relational data, complex queries

Core Concepts

Tables

DynamoDB stores data in tables. Each table stores a collection of items (rows). Unlike SQL, tables don't have a fixed schema — items can have different attributes.

Items and Attributes

An item is a collection of attributes (like a JSON object). Every item must have the table's primary key, but other attributes are flexible.

Primary Key

Every table must have a primary key. Two options:

Simple primary key — Just a Partition Key (hash key)
Composite primary key — A Partition Key + Sort Key (range key)

GSI and LSI (Secondary Indexes)

DynamoDB can only efficiently query by primary key. For other access patterns, you create:

Global Secondary Index (GSI) — A new partition key + optional sort key, on any attributes
Local Secondary Index (LSI) — Same partition key, different sort key

Setting Up

AWS SDK v3 (JavaScript):

bash

npm install @aws-sdk/client-dynamodb @aws-sdk/lib-dynamodb

Local Development with DynamoDB Local:

bash

docker run -p 8000:8000 amazon/dynamodb-local

javascript

import { DynamoDBClient } from '@aws-sdk/client-dynamodb';
import { DynamoDBDocumentClient } from '@aws-sdk/lib-dynamodb';

const client = new DynamoDBClient({
  region: 'us-east-1',
  // For local development:
  // endpoint: 'http://localhost:8000',
  // credentials: { accessKeyId: 'local', secretAccessKey: 'local' },
});

const docClient = DynamoDBDocumentClient.from(client);

Example

javascript

import { DynamoDBClient } from '@aws-sdk/client-dynamodb';
import { DynamoDBDocumentClient, PutCommand, GetCommand } from '@aws-sdk/lib-dynamodb';

const client = new DynamoDBClient({ region: 'us-east-1' });
const docClient = DynamoDBDocumentClient.from(client);

// Write an item
await docClient.send(new PutCommand({
  TableName: 'Users',
  Item: {
    PK: 'USER#alice@example.com',
    SK: 'PROFILE',
    name: 'Alice Smith',
    role: 'admin',
    createdAt: new Date().toISOString(),
  },
}));

// Read an item
const result = await docClient.send(new GetCommand({
  TableName: 'Users',
  Key: { PK: 'USER#alice@example.com', SK: 'PROFILE' },
}));

console.log(result.Item);

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