Databases

Question 1

What is ElasticCache?

Answer 1

an in memory cache in the cloud.
* Allows you retrieve data a lot quicker, by pulling data from memory cache in the cloud rather than slower disk-based databases.
supports master and slave replication.

Question 2

What are the two types of Elacticcache ?

Answer 2

Memcached

Redis (opensource in-memory key-value store)

Question 3

AWS Database types?

Answer 3

RDS-OLTP
DynamoDB (No SQL)
RedSHift (Amazon’s OLAP data warehouse product)
Elasticache

Question 4

AWS Database RDS OLTP examples:

Answer 4

SQL 
MySQL
PostgreSQL
Oracle
Aurora (AWS MySQL & PostgreSQL compatible DB)
MariaDB

Question 5

RDS Backups.

Answer 5

There are two:

1) Automated backups
2) Database snapshots

Question 6

RDS Backup - Automated backup - key points:

Answer 6

1) Retention 1 - and 35 days.
2) Backup is a fully daily snapshot
3) Stores transactional logs
4) Recovery will first choose the most recent daily backup then apply transaction logs for that day.
5) enabled by default

Question 7

RDS Backup - database snapshots - key points:

Answer 7

1) Always manual. (User initiated)
2) Are restored even after you delete the original RDS instance. A restored RDS instance will be a new RDS instance with a new DNS endpoint.

Question 8

Database Encryption:

Answer 8

Encryption at Rest:

• MySQL, Oracle, SQ Server, PostgreSQL, MariaDB and Aurora.
• Encryption is done using the AWS key management service.
• backups, replicas and snapshots are encrypted.

Question 9

Database and Multi AZ :

Answer 9

Designed for DR recovery. Writes to 1 Database is replicated to database 2.
* Failover is automated.
* not a performance improvement.
Available: SQL Server, Oracle, MySQL, PostgreSQL, MariaDB, Aurora.

Question 10

Databases and Read Replicas:

Answer 10

This is designed to increase Database performance by reading out, but not for redundancy.
you have a read replica of a read replica (some latency)
you have 5 read replicas per production database.
This is asynchronous.
Read replicas can have multi-AZ enabled.
Read Replicas can be promoted to their own DB.
Must have automatic backups turned on in order to deploy a read-replica.
Can enable encryption even if the primary database is not encrypted.

Question 11

What is DynamoDB ?

Answer 11

It is a fast and flexible NoSQL Database service. It provides:
consistent, single digit millisecond latency at scale.
Great fit for: mobile, web, gaming, ad-tech, IoT.

Question 12

DynamoDB Data points:

Answer 12

1) Stored on SSD.
2) Spread across 3 geographically distinct data centres.
3) Eventual consistent reads. (best read performance)
4) Strongly consistent reads. (best write performance)

Question 13

DynamoDB Pricing ?

Answer 13

Provisioned through capacity.

• Write throughput.
• read throughput
• storage costs.

Question 14

What is RedShift ?

Answer 14

RedShift is Amazon’s dataware house service in the cloud. (petabyte scale)

Question 15

Red Shift Costs ?

Answer 15

1) Compute node hours
2) backup
3) data transfer within a VPC.

Question 16

What is OLAP ?

Answer 16

Online Analytics Processing

Question 17

Redshift Config :

Answer 17

Single Node or Multi node config.

In a multi node setup there is a leader node and compute nodes. (max 128 compute nodes)

Question 18

RedShift Node Info:

Answer 18

Single Node (160Gb)

Question 19

RedShift data points:

Answer 19

1) columnar data storage: data is stored in columns not rows. (fewer I/O, improved performance on queries).
2) Adv. compression.
3) Massively parallel processing (MPP) It scales fast and easily))

Question 20

RedShift Security:

Answer 20

1) Data in transit uses SSL
2) Data at rest uses AES-256
3) RedShift takes care of key management (you can manage your own however)

Question 21

RedShift Availability:

Answer 21

Only available in 1 AZ.

Can restore snapshots to new AZs in the event of an outage.

Question 22

What is Aurora?

Answer 22

A bespoke database created by AWS. It is compatible with MySQL and PostgreSQL.

Question 23

Aurora Data Points:

Answer 23

1) 5x better performance than MySQL

2) 1/10th of the cost of MySQL.

Question 24

Aurora Scaling:

Answer 24

Storage: starts with 10GB, then auto scales at 10GB increments.
Compute: scale up to 32vCPUS & 244GB Ram
Availability: 2x copies of your data per availability zone, with 3 availability zones. (Can handle the loss of up to 2 copies of data with affecting DB write availability, and can handle the loss of 3 copies of data before affecting DB read availability).

Question 25

Aurora Replicas:

Answer 25

2 types of replicas are available.
it supports up to 15 replicas.
it allows for MySQL read replicas (up to 5 replicas)
replicas can be multi AZ.