DynamoDB

Question 1

What is AWS DynamoDB?

Answer 1

DynamoDB is a fast and flexible NoSQL DB service for all applications that need consistent, single-digit milliscond latency at any scale

Question 2

Does DynamoDB support document data models?

Answer 2

Yes

Question 3

Does DynamoDB support key-value data models?

Answer 3

Yes

Question 4

On what type of storage is DynamoDB data stored?

Answer 4

On SSD storage

Question 5

How does Dynamo DB provide data redundancy?

Answer 5

Data in DynamoDB is spread across 3 geographically distinct data centers

Question 6

What is the data consistency model for DynamoDB?

Answer 6

Eventually Consistent Reads by Default

Strongly Consistent Reads as an option

Question 7

Roughly when are Eventually Consistent Reads consistent?

Answer 7

Data consistency is usually reached within 1 second

Question 8

What are Strongly Consistent Reads?

Answer 8

A strongly consistent read reflects all writes that received a successful response prior to the read.

Question 9

What does DAX stand for?

Answer 9

DynamoDB Accelerator

Question 10

What is AWS DAX?

Answer 10

Fully managed, highly-available in-memory cache for DynamoDB

Question 11

What is the performance improvement offered by AWS DAX?

Answer 11

10x performance improvement over DB standalone

Reduces request time from milliseconds to microseconds

Question 12

What does the developer need to do to manage the logic in AWS DAX?

Answer 12

Nothing. The caching logic is fully managed by AWS

Question 13

Can AWS DAX also provide write speedup?

Answer 13

No, it is a write-through cache

Write goes to DB, then synchronously to cache, so there’s actually a tiny bit of latency

Question 14

What does DynamoDB Transactions assist with?

Answer 14

Atomic operations

(Think money transfer, can’t debit one account without crediting another)

Question 15

How does using DynamoDB Transactions affect read/write capacity?

Answer 15

Transactions does 2 underlying reads or writes of every item in the transaction, one to prepare, and one to commit.

Question 16

What is DynamoDB On-Demand Capacity?

Answer 16

Pay-per-request pricing

Question 17

What is the minimum capacity required for DynamoDB On-Demand capacity?

Answer 17

There is none!

Question 18

What is the pricing model for DynamoDB On-Demand Capacity?

Answer 18

• No charge for read/write while the table is idle, only for storage and backups
• Pay more per request than with provisioned capacity

Question 19

What is the recommended use case for DynamoDB On-Demand Capacity?

Answer 19

New Product Launches, when you don’t have a sense ahead of time of how much traffic to expect

Question 20

What is the maximum amount of data on which DynamoDB Transactions can operate at any time?

Answer 20

25 items or 4MB of data

Question 21

What is the performance hit of AWS DynamoDB On-Demand Backup and Restore?

Answer 21

There is zero impact on table performance

Question 22

What is the availability hit of using DynamoDB On-Demand Backup & Restore?

Answer 22

There is zero impact on table availability

Question 23

What is the data consistency model for DynamoDB On-Demand Backup and Restore?

Answer 23

Data is consistent within seconds

Question 24

What is the data retention model for DynamoDB On-Demand Backup & Restore?

Answer 24

Data is retained until deleted

Question 25

Can you have a DynamoDB On-Demand Backup in the same region as the source table?

Answer 25

**Yes**

Question 26

Can you have a DynamoDB On-Demand Backup in a different region from your source table?

Answer 26

**No**

Question 27

What does **PITR** stand for?

Answer 27

**P**oint-**I**n-**T**ime **R**ecovery

Question 28

What is the purpose of DynamoDB PITR?

Answer 28

To **protect against accidental writes and deletes**

Question 29

How far back can you restore using PITR?

Answer 29

Restore to **any point in the last 35 days**

Question 30

How is DynamoDB backup data stored?

Answer 30

DynamoDB keeps **incremental backups** of your data

Question 31

Is DynamoDB PITR enabled by default?

Answer 31

**No**

Question 32

With DynamoDB PITR, how far back is the latest restorable time stamp?

Answer 32

Typically **5 minutes** in the past

Question 33

What is a **DynamoDB Stream?**

Answer 33

A **time-ordered sequence of item-level changes in a table**

Question 34

How long is info stored in DynamoDB Stream?

Answer 34

Info is stored for **24 hours**

Question 35

If you wanted to imitate a stored procedure functionality in Dynamo DB, how might you do it?

Answer 35

Combine **Streams** with **AWS Lambda Functions**

Question 36

What does **DMS** stand for?

Answer 36

**D**atabase **M**igration **S**ervice

Question 37

What are some of the ways you can get security in DynamoDB?

Answer 37

* Encryption at Rest (with KMS) * site-to-site VPN * Direct Connect * IAM Policies & Roles (or fine-grained access) * mornitoring using CloudWatch and CloudTrail * VPC endpoints

Question 38

How is data in DynamoDB stored?

Answer 38

It is stored **in JSON Format**

Question 39

What is the maximum allowed item size in DynamoDB?

Answer 39

The _key and value combined_ can be at most **400KB**

Question 40

Which storage service is best for storing object metadata?

Answer 40

**DynamoDB**