AWS Service - DynamoDB

DynamoDB

Overview
- Fully managed, highly available with replication across multiple AZs
- NoSQL database - not a relational database - with transaction support
- Scales to massive workloads, distributed database
- Millions of requests per seconds, trillions of row, 100s of TB of storage
- Fast and consistent in performance (single-digit millisecond)
- Integrated with IAM for security, authorization and administration
- Low cost and auto-scaling capabilities
- No maintenance or patching, always available
- Standard & Infrequent Access (IA) Table Class
Introduction
- DynamoDB is made of Tables
- Each table has a Primary Key (must be decided at creation time)
- Each table can have an infinite number of items (rows)
- Each item has attributes (can be added over time – can be null)

Maximum size of an item is 400KB
Data types supported are
- Scalar Types - String, Number, Binary, Boolean, Null
- Document Types - List, Map
- Set Types - String Set, Number Set, Binary Set
Therefore, in DynamoDB you can rapidly evolve schemas

DynamoDB Capacity Modes
- Control how you manage your table’s capacity (read/write throughput)
- Provisioned Mode (default)
  - You specify the number of reads/writes per second
  - You need to plan capacity beforehand
  - Pay for provisioned Read Capacity Units (RCU) & Write Capacity Units (WCU)
  - Possibility to add auto-scaling mode for RCU & WCU
- On-Demand Mode
  - Read/writes automatically scale up/down with your workloads
  - No capacity planning needed
  - Pay for what you use, more expensive ($$$)
  - Great for unpredictable workloads, steep sudden spikes
DynamoDB Accelerator (DAX)
- Fully-managed, highly available, seamless in-memory cache for DynamoDB
- Help solve read congestion by caching
- Microseconds latency for cached data
- Doesn’t require application logic modification (compatible with existing DynamoDB APIs)
- 5 minutes TTL for cache (default)

DynamoDB Stream Processing
- Ordered stream of item-level modifications (create/update/delete) in a table
- Use cases
  - React to changes in real-time (welcome email to users)
  - Real-time usage analytics
  - Insert into derivative tables
  - Implement cross-region replication
  - Invoke AWS Lambda on changes to your DynamoDB table

DynamoDB Global Tables
- Make a DynamoDB table accessible with low latency in multiple-regions
- Active-Active replication
- Applications can READ and WRITE to the table in any region
- Must enable DynamoDB Streams as a pre-requisite

DynamoDB - Time To Live (TTL)
- Automatically delete items after an expiry timestamp
- Use cases: reduce stored data by keeping only current items, adhere to regulatory obligations, web session handling

DynamoDB Backups for disaster recovery
- Continuous backups using point-in-time recovery (PITR)
  - Optionally enabled for the last 35 days
  - Point-in-time recovery to any time within the backup window
  - The recovery process creates a new table
- On-demand backups
  - Full backups for long-term retention, until explicitely deleted
  - Doesn’t affect performance or latency
  - Can be configured and managed in AWS Backup (enables cross-region copy)
  - The recovery process creates a new table
DynamoDB Integration with Amazon S3
- Export to S3 (must enable PITR)
  - Works for any point of time in the last 35 days
  - Doesn’t affect the read capacity of your table
  - Perform data analysis on top of DynamoDB
  - Retain snapshots for auditing
  - ETL on top of S3 data before importing back into DynamoDB
  - Export in DynamoDB JSON or ION format

Import from S3
- Import CSV, DynamoDB JSON or ION format
- Doesn’t consume any write capacity
- Creates a new table
- Import errors are logged in CloudWatch Logs

Relevant Doc:

Disclaimer: This is a personal blog that might come in handy when I suffer from Dementia in future.

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