In short
DynamoDB is AWS's fully managed NoSQL database. No servers to patch, it scales for you, and you can pay per request. The catch: you design around your queries from day one.
Amazon's fully managed, serverless NoSQL key-value/document database — popular for AWS-based serverless architectures needing predictable low-latency access at scale.
Think of it like this
The hostel mess hatch
At the mess you don't run the kitchen. You walk up to the hatch, ask for something on the menu, and a plate slides out. The kitchen scales up for exam week on its own. But you can only order what's on the menu. DynamoDB works like that hatch.
Watch it happen
One table, keyed for queries
1/5Each item has a partition key (PK) and a sort key (SK). Users and orders share one table.
The big ideas
What you need to know
Fully managed
AWS runs the servers, replication and backups. You create a table and start reading and writing.
Partition and sort keys
The partition key spreads items across storage; the sort key orders items inside a partition.
Query, not Scan
Query uses keys and is fast. Scan reads the whole table and gets slow and expensive.
Secondary indexes
A GSI gives the table another key, so a second access pattern can also use Query.
See it in code
Walk through the code
1import { DynamoDBClient } from "@aws-sdk/client-dynamodb";2import { DynamoDBDocumentClient, QueryCommand } from "@aws-sdk/lib-dynamodb";3 4const db = DynamoDBDocumentClient.from(new DynamoDBClient({ region: "ap-south-1" }));5 6const { Items } = await db.send(new QueryCommand({7 TableName: "app",8 KeyConditionExpression: "PK = :pk AND begins_with(SK, :sk)",9 ExpressionAttributeValues: { ":pk": "USER#7", ":sk": "ORDER#" },10 ScanIndexForward: false,11 Limit: 10,12}));1/3The document client lets you use plain JS objects. ap-south-1 is the Mumbai region.
Run it with AWS credentials set up, or point the client at DynamoDB Local to practise for free.
Save yourself the pain
Common mistakes
Oops
Designing tables like SQL and planning to Scan with filters.
Do this instead
Scan reads everything and you pay for all of it. Design keys and GSIs so each screen is a Query.
Oops
Choosing a partition key with only a few possible values, like status.
Do this instead
A few hot keys overload a few partitions. Pick keys with lots of variety, like userId.
Your mission
DynamoDB Local
Quick check
You need 'all orders for user 7, newest first'. What's the DynamoDB-friendly design?
Go deeper
- 1Read AWS's documentation on DynamoDB's single-table design philosophy.
- 2Understand its pricing model (provisioned/on-demand capacity) at a high level.
- 3Compare it to self-hosted MongoDB in terms of operational overhead.
More topics at this stop
NoSQL vs SQL
MongoDB Basics
Document Model
CRUD Operations
Aggregation Pipeline
Indexing in MongoDB
Redis Basics
Key-Value Store
Data Modeling in NoSQL
When to Use NoSQL
Cassandra (Overview)
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