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Sudarshan Yadav
Sudarshan Yadav

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📅 Day 22 | AWS DynamoDB — Serverless NoSQL Database in AWS ⚡☁️

# 📅 Day 22 | AWS DynamoDB — Serverless NoSQL Database in AWS ⚡☁️

Today, I learned about AWS DynamoDB, a fully managed, serverless, NoSQL database service designed to provide fast and predictable performance with seamless scalability.

DynamoDB is a key-value and document database that delivers single-digit millisecond performance at any scale. It’s a favorite for DevOps and Cloud Engineers because it removes the administrative burden of operating and scaling distributed databases.

⚡ AWS DynamoDB – DevOps Explanation

What is AWS DynamoDB?

AWS DynamoDB is a Serverless NoSQL Database that allows you to store and retrieve any amount of data and serve any level of request traffic.

Unlike relational databases (RDS), DynamoDB is non-relational, meaning it doesn't use fixed schemas or complex joins. AWS handles the:

  • Hardware provisioning
  • Setup and configuration
  • Replication and software patching
  • Cluster scaling

Why DevOps Engineers Use DynamoDB

DynamoDB is the go-to choice when:

  • You need extreme scale (millions of requests per second)
  • You require consistent low latency (single-digit milliseconds)
  • You want a serverless architecture (no instances to manage)
  • You need global availability (Global Tables)

Core Concepts (The Fundamentals)

  • Tables: Similar to a table in SQL, but with no fixed schema.
  • Items: Similar to a "row." Each item is a collection of attributes.
  • Attributes: Similar to a "column." Can be strings, numbers, binaries, or even JSON (Maps/Lists).
  • Primary Key: Must be defined at creation. It consists of:
    • Partition Key (PK): Used for internal data distribution.
    • Sort Key (SK): (Optional) Used to sort data within a partition.

DynamoDB Features & Architecture

  • High Availability: Data is automatically replicated across three Availability Zones (AZs) within a region.
  • Read Consistency: * Eventually Consistent (Default) – Best performance, lowest cost.
    • Strongly Consistent – Returns the most up-to-date data.
  • DynamoDB Streams: Captures item-level changes (Insert/Update/Delete) and triggers AWS Lambda—perfect for event-driven apps.
  • TTL (Time to Live): Automatically deletes expired items to reduce storage costs.

Capacity Modes (How you pay)

  1. On-Demand: You pay per request. Best for unpredictable workloads or new apps.
  2. Provisioned: You specify RCU (Read Capacity Units) and WCU (Write Capacity Units). Best for predictable traffic and cost control (supports Auto Scaling).

Indexing for Performance

Since you can only query by Primary Key, you use Indexes to query other attributes:

  • Local Secondary Index (LSI): Same Partition Key, different Sort Key. (Must be created with the table).
  • Global Secondary Index (GSI): Different Partition Key AND different Sort Key. (Can be created anytime).

Security in DynamoDB

  • IAM: Control who can read/write to specific tables.
  • Encryption at Rest: All data is encrypted by default using AWS KMS.
  • VPC Endpoints: Keep traffic within the AWS network (Gateway Endpoint).
  • Fine-Grained Access Control: Using IAM policies to restrict access to specific items or attributes.

Common Use Cases

  • Serverless Apps: Paired with AWS Lambda and API Gateway.
  • Session Management: Storing user sessions for web applications.
  • Gaming: Storing leaderboards and player profiles.
  • IoT: Ingesting massive amounts of sensor data.

Advantages

  • No Servers to Manage: Zero operational overhead.
  • Auto-Scaling: Grows and shrinks based on traffic.
  • Enterprise Grade: Supports ACID transactions and 99.999% availability with Global Tables.
  • Performance at Scale: Latency does not increase as the database grows.

Limitations

  • No Joins: You must model data to avoid needing joins.
  • Query Limitations: You cannot perform complex SQL-like queries easily.
  • Item Size: Maximum size per item is 400 KB.

Interview One-Line Answer

AWS DynamoDB is a fully managed, serverless NoSQL database that provides consistent, single-digit millisecond latency at any scale. It supports both document and key-value data models, offers built-in security, backup/restore, and multi-region replication via Global Tables.

Thank You

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