NoSQL/DynamoDB

Question 1

What is a partition key in DynamoDB?

Answer 1

Can act as a primary key. Determines what data is stored together.

Question 2

What is a sort key in DDB?

Answer 2

Determines sort order of partitions. Optionally part of composite PK along with partition key.

Question 3

1 WCU means you can write ___ of data per second

Answer 3

1 KB

Question 4

1 RCU means you can read ____ of data per second.

Answer 4

4 KB

Question 5

What are the two types of backups for DDB?

Answer 5

On Demand and Point In Time Recovery.

Question 6

When do on demand backups get deleted?

Answer 6

When you delete them, no automatic deletion.

Question 7

When are point in time recovery snapshots deleted?

Answer 7

Auto after 35 days

Question 8

How far behind are point in time recovery backups?

Answer 8

One second

Question 9

How are WCUs and RCUs handled in on demand tables?

Answer 9

You pay a price per million RCUs or WCUs. Scaling done for you automatically.

Question 10

How are WCUs and RCUs handled with a Provisioned table?

Answer 10

RCU and WCU set per table.

Question 11

What are the two ways to read data from DynamoDB?

Answer 11

Query and Scan

Question 12

What is the advantage of Query in DDB?

Answer 12

Capacity consumed is only on what is returned by query.

Question 13

What is the disadvantage of Query in DDB?

Answer 13

Not flexible, can only query on PK or PK/SK

Question 14

What is the advantage of Scan in DynamoDB?

Answer 14

You can query on any attribute

Question 15

What is the disadvantage of Scan in DDB?

Answer 15

Capacity consumed for every item scanned through

Question 16

What is a Local Secondary Index?

Answer 16

Alternative view of table that uses an alternative sort key

Question 17

When can LSI’s be created?

Answer 17

Only when table is created

Question 18

What is a Global Secondary Index?

Answer 18

Alternative partition key or partition key/sort key combination for a table

Question 19

When can GSI’s be created?

Answer 19

Any time

Question 20

What is a stream in DDB?

Answer 20

A 24 hour rolling time ordered list of item changes in a table

Question 21

In DDB, what is the primary use of a trigger?

Answer 21

When an attribute for an item is changed, we can send an event using streams to a lambda function to take some sort of action.

Question 22

What is the purpose of a Global table?

Answer 22

Allow for global high availability and global disaster recovery and business continuity.

Question 23

How is DAX highly available?

Answer 23

There is a primary node and read replicas distributed across multiple A Z ‘s within a VPC.

Question 24

What is the primary use of DAX?

Answer 24

Allows for caching of reads from DynamoDB table. This can speed up reads and allow for better scaling.

Question 25

What is Elasticache?

Answer 25

An in-memory, high performance database (cache) that lives within an application.

Question 26

What is the main use of Athena?

Answer 26

Read data that is stored in S3 using SQL queries

Question 27

Where is Redshift data backed up to?

Answer 27

S3

Question 28

How often do automatic backups of redshift occur?

Answer 28

Every 8 hours or 5 GB of data consumed