# 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)
        
    
    ![](https://cdn.hashnode.com/res/hashnode/image/upload/v1728221042899/f909f0a0-b7d7-4b3f-a60c-a7aa66ad8339.png align="center")
    
    * 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)
        

![](https://cdn.hashnode.com/res/hashnode/image/upload/v1728221268170/0a4cbd93-1ba0-495b-94bd-b2c9efd9661f.png align="center")

* **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
            

![](https://cdn.hashnode.com/res/hashnode/image/upload/v1728221524498/57a4b6dc-e572-45c2-a645-db2b8437f9ea.png align="center")

* **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
        

![](https://cdn.hashnode.com/res/hashnode/image/upload/v1728221628790/34fc510f-b6be-4018-908a-8bc5d4473d13.png align="center")

* **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
        

![](https://cdn.hashnode.com/res/hashnode/image/upload/v1728221839528/c61de345-7047-4a7d-9a43-3fa6152d1c4e.png align="center")

* **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
            
    
    ![](https://cdn.hashnode.com/res/hashnode/image/upload/v1728227088065/e426137c-bb7b-4beb-acdf-e318d8aa4fa4.png align="center")
    
    * 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
            

![](https://cdn.hashnode.com/res/hashnode/image/upload/v1728227103217/e5e5808a-f4cf-4d9d-8c62-2ee5baec98ba.png align="center")

**Relevant Doc:**

[https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/Introduction.html](https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/Introduction.html)

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