Amazon DynamoDB
- Fully managed, highly available with replication across multiple AZs
- NoSQL DB - not RDB - with transaction support
- Scales to massive workloads, distributed DB
- Millions of requests per sec, 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
Basic Concept
- Made of Tables
- Each table has a Primary Key (must be decided at creation time)
- Each table can have 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
Read/Write Capacity Modes
- control how to manage tableโs 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
- Doesnโt require application logic modification (compatible with existing DynamoDB APIs)
Stream Processing
- Order stream of item-level modifications (create/update/delete) in a table
- DynamoDB Streams
- 24hrs retention
- Limited # of consumers
- Process using Lambda triggers, or DDB Stream Kinesis adapter
- Kinesis Data Streams (newer)
- 1year retention
- High # of consumers
- Process using Lambda, Kinesis Data Analytics, Data Firehose, AWS Glue Streaming ETL
Global Tables
- Make DDB table accessible with low latency in multiple-regions
- Active-Active replication
- Apps can READ and WRITE to the table in any region
- Must enable DDB Streams as a pre-requisite
Time To Live (TTL)
- Automatically delete items after an expiry timestamp
Backups for DR
- 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 explicitly deleted
- Doesnโt affect performance or latency
- Can be configured and managed in AWS Backup (enables cross-region copy)
- The recovery process creates a new table
References