Databases - DynamoDB

Question 1

What is DynamoDB

Answer 1

fast and flexible NoSQL database service for all apps that need consistent, single-digit millisecond latency at any scale.

Question 2

Is DynamoDB fully managed?

Answer 2

Yes

Question 3

What models does DynamoDB support?

Answer 3

Document, key-value

Question 4

Uses for DynamoDB

Answer 4

mobile, web, gaming, ad-tech, IoT

Question 5

Where is data in DynamoDB stored?

Answer 5

SSD Storage

Question 6

Where is DynamoDB spread?

Answer 6

across 3 geographically distinct data centers (not AZs)

Question 7

Default consistency model for DynamoDB

Answer 7

Eventual Consistent Reads. Strongly consistent reads is the other

Question 8

Eventual Consistent Reads

Answer 8

Consistency across all copies of data is usually reached within 1 second. repeating a read after a short time should return the updated data (best read performance)

Question 9

Strongly Consistent Reads

Answer 9

returns the result that reflects all writes that received a successful response prior to the read. May not be available if there is an outage or delay. Not supported across AWS regions.

Question 10

If low latency is important

Answer 10

pick Eventual consistent reads. Otherwise, pick strongly consistent reads

Question 11

DynamoDB pricing

Answer 11

Provisioned throughput capacity, reading, writing and storage of data in tables

Question 12

How expensive is DynamoDB?

Answer 12

Expensive for writes, cheap for reads

Question 13

Use case for DynamoDB

Answer 13

If DB is read-heavy, scalabilty and good performance are important, SQL is not necessary

Question 14

default read and write capacity units when creating a DynamoDB table

Answer 14

5, 5

Question 15

can you purchase reserved capacity?

Answer 15

Yes, 1 or 3-year terms

Question 16

Item

Answer 16

Row

Question 17

Important metrics to know

Answer 17

Read capacity Units, Write capacity units (both provisioned/consumed)

Question 18

What are some key security features?

Answer 18

Encryption at rest using KMS, AES-256 encryption; authentication and authorization

Question 19

What are tables?

Answer 19

a collection of items that are schema less with a limit of 256 tables per region

Question 20

What are items?

Answer 20

a collection of attributes that used primary keys to uniquely identify each item in a table and secondary indexes to provide more querying flexibility.

Question 21

What are attributes?

Answer 21

a fundamental data element

Question 22

What is a primary key?

Answer 22

uniquely ids each item in a table and no two items can have the same key

Question 23

What the different types of primary keys?

Answer 23

A simple partition key with on attribute and a composite partition/sort key with two attributes

Question 24

What are secondary indexes?

Answer 24

Query data in a table using an alternate key, in addition to queries of primary

Question 25

What is a global secondary key?

Answer 25

Partition and sort key that can be different than the base table. Primary key can be partition key or sort key. Up to 20 GSI can be defined.

Question 26

What is a local secondary key?

Answer 26

Partition has the same partition key as the base table but as different sort key. Must be partition/sort key. Up to 5 LSIs can be defined.

Question 27

What is a DynamoDB stream?

Answer 27

a feature that captures data modification events in tables.

Question 28

What is name convention for a DynamoDB stream?

Answer 28

streams.dynamodb.amazonaws.com

Question 29

What is a stream record?

Answer 29

each modification event is represented as a stream record. Contains a table name, timestamp and other metadata. Streams last for 24 hours.

Question 30

What is a shard?

Answer 30

A group of stream records that acts a container of the required information to access and iterate through these records.

Question 31

What is DAX?

Answer 31

fully managed, HA, in-memory cache for DDB. Useful for read-intensive workloads, but not write.

Question 32

Why use DAX?

Answer 32

microsecond response times for access eventually consistent data. Very heavy duty loads and scaling on-demand

Question 33

What are DAX use cases?

Answer 33

fastest possible response for reads; app that read a small number of items more frequently than others.

Question 34

How does Dynamo differ from RDS?

Answer 34

NoSQL; millisecond performance; supports tables in any size;

Question 35

How is DDB replication?

Answer 35

replicates across 3 AZs of your choice.

Question 36

How is maintenance conducted?

Answer 36

No maintenance since DynamoDB is serverless

Question 37

What are the popular use cases for DynamoDB?

Answer 37

Internet-scale applications, real-time bidding, shopping carts, and customer preferences, content management, personalization and mobile applications.