DynamoDB Flashcards
Where is DynamoDB data stored?
On SSD storage
How does Dynamo DB provide data redundancy?
Data in DynamoDB is spread across 3 geographically distinct data centers
What is the data consistency model for DynamoDB?
Eventually Consistent Reads by Default
Strongly Consistent Reads as an option
Roughly when are Eventually Consistent Reads consistent?
Data consistency is usually reached within 1 second
What are Strongly Consistent Reads?
A strongly consistent read reflects all writes that received a successful response prior to the read.
What is AWS DAX?
Fully managed, highly-available in-memory cache for DynamoDB
What is the performance improvement offered by AWS DAX?
10x performance improvement over DB standalone
Reduces request time from milliseconds to microseconds
Can AWS DAX also provide write speedup?
Yes, it is a write-through cache
What does DynamoDB Transactions assist with?
Atomic operations
(Think money transfer, can’t debit one account without crediting another)
How does using DynamoDB Transactions affect read/write capacity?
Transactions does 2 underlying reads or writes of every item in the transaction, one to prepare, and one to commit.
What is DynamoDB On-Demand Capacity?
Pay-per-request pricing
What is the minimum capacity required for DynamoDB On-Demand capacity?
There is none!
What is the pricing model for DynamoDB On-Demand Capacity?
- No charge for read/write while the table is idle, only for storage and backups
- Pay more per request than with provisioned capacity
What is the recommended use case for DynamoDB On-Demand Capacity?
New Product Launches, when you don’t have a sense ahead of time of how much traffic to expect
What is the maximum amount of data on which DynamoDB Transactions can operate at any time?
25 items or 4MB of data
What is a DynamoDB Stream?
A time-ordered sequence of item-level changes in a table
