Section 21: Databases in AWS

Question 1

Data Types
P228

Answer 1

• RDBMS(=SQL): RDS,Aurora - Great for joins
• NoSQL database: DynamoDB(json), ElastiCache(key/value pairs), Neptune(graphs) -
  no joins,no SQL
• Object Store: S3(for big objects) / Glacier(for backups / archives)
• Data Warehouse:(= SQL Analytics): Redshift,Athena
• Search: ElasticSearch(Json) - Free text,unstructured search
• Graphs: Neptune - displays relationships between data

Question 2

RDS Overview

Answer 2

• Managed PostgreSQL/ MySQL/ Oracle/ SQL Server
• Must provision an EC2 instance and EBS volumes type and size(happens in backround)
• Support Read Replicas and Multi AZ
• Security through IAM, Security groups,SSL
• Backup/ Snapshot/ Point in time restore feature
• Managed and Scheduled maintenance
• Monitoring through Cloudwatch
• Use case: Store relational datasets, perform SQL queries,transactional inserts/ update/ delete

Question 3

Aurora Overview

Answer 3

• Compatible API for PostgreSQL / MySQL
• Data is held in 6 replicas, across 3 AZ
• Auto healing Capabilities
• Read replicas can be Global
• Aurora Serverless - for unpredictable / intermittent workloads
• Aurora Multi-Master - for continuous writes failover
• Use Case: same as RDS but with less maintenance, more felxibility, more performance

Question 4

ElasticCache Overview

Answer 4

• Managed Redis / Memcached
• In-memory data store,sub-millisecond latency
• Must provision an EC2 instance type
• Support for Clustering and Multi AZ, Read Replicas
• Security through IAM, Security Groups
• Backup / Snapshot / Point in tme restore feature
• Managed and scheduled maintenance
• Monitoring through Cloudwatch
• Use case: Key/Value stiore, frequent reads, less writes

Question 5

DynamoDB Overview
P232

Answer 5

• AWS proprietary technology, managed NoSQL database
• Serverless, provisioned capacity,auto scaling
• Can replace ElasticCache as a key/value store
• Highly Available. Multi AZ by default,Read and Write is decoupled,Dax for read cache
• Security,authentication is done by IAM
• DynamoDB Streams to integrate with AWS Lambda
• Backup/ Restore features
• Monitoring through CloudWatch
• Use Case: Serverless applications development,has transactions capabilities from Nov 2018

Question 6

Athena Overview

Answer 6

• Fully serverless database with SQL capabilities
• Used to query data in S3
• Pay per query
• Output result back to S3
• Secured through IAM
• Use Case: One time SQL queries, serverless queries on S3,log analytics

Question 7

Redshift Overview

Answer 7

• Redshift is based on PostgreSQL but its not used for OLTP(Online Transaction Processing)
• Its OLAP - online analytical processing(analytics and data warehousing)
• 10x better performance than other warehousing
• Columnar storage of data
• Massively Parallel Query Execution
• Has a SQL interface for performaning the queries

Question 8

What is AWS Glue

Answer 8

• Managed extract, transform and load service
• Useful to prepare and transform data analytics
• Fully serverless service
• Exampe: Extract data from S3 backet, transform it and loads on in Redshift Data warehouse

Question 9

What is AWS Neptune
P237

Answer 9

• Fully managed graph database
• When do we use Graphs?
  1) High relationship data
  2) Social network
  3) Knowledge graphs
• High available across 3 AZ
• Point in time recovery
• Support for KMS encryptions at rest

Question 10

What is AWS OpenSearch?

Answer 10

• AWS OpenSerach is successor to Amazon ElasticSearch
• Used to search and index of data

Question 11

CloudWatch Logs Agent & Unified Agent

Answer 11

• For virtual servers(EC2 instances ,on-premise servers)
  1) Cloudwatch Logs Agent
  
  • Old version of the agent
  • Can only send to CloudWatch Logs

2) CloudWatch Unified Agent
- Collect additional system-level metrics such as RAM, processes
- Collect logs to send to CloudWatch logs
- Centralized configurations using SSM Parameter Store

Question 12

What is AWS CloudTrail?

Answer 12

• Provides governance, compliance and audit for your AWS account
• Keeps an history of events/ PAI calls made with your AWS account.
• Can put logs from CloudTrail into CloudWatch Logs or S3.

Question 13

What 3 AWS CloudTrail events do you get?
P250

Answer 13

1) Management event
2) Data events