- Fully managed NoSQL database service.
- You cannot select Availability Zone while creating a DynamoDB table.
- No Secondary Indexes created by default. Must be created manually if required.
- Provisioned capacity set to 5 reads and 5 writes by default.
- Amazon DynamoDB stores three geographically distributed replicas of each table to enable high availability and data durability.
- Two Consistency models:
Eventually Consistent Reads (Default): Maximizes read throughput but change might not reflect immediately.
Strongly Consistent Reads: Can be request and give read speeds of less quicker. - A single
Scan
will only return a result set that fits within the 1 MB size limit.
DynamoDB
AWS Certified Solution Architect – Points to remember (RDS)
- Relational Database Service.
- Supported databases (AMMMOP – If it helps!)
Amazon Aurora
MariaDB
Microsoft SQL
MySQL
Oracle
PostgreSQL - Contrary to DynamoDB, for RDS you can select the availability Zone for RDS in a region.
- There is no easy way to encrypt an all already existing unencrypted RDS instance.
You will have to make a snapshot add and encryption key to snapshot and restore the session using this encrypted snapshot. - All database backups are automatically deleted once you delete the RDS instance.
- Default backup retention period is 1 day and can be extended up to 35 days.
- Read replicas are Asynchronous and Multi-AZ is Synchronous.
- Anything with read performance improvement points to Read Replicas and Anything with availability points to Multi-AZ Deployments.
- Backups are automatically deleted if you delete the RDS instance. May be there is still a snapshot if the person who deleted selected this option.