Section 3 - Relation Databases (RDS)

Question 1

When would we use an RDS database?

Answer 1

• RDS is generally used for Online Transaction Processing (OLTP) workloads.

Question 2

Difference bwteen OLTP and OLAP?

Answer 2

Online Transaction Processing(OLTP):

• Processes data from transactions in real-time e.g. customer orders, banking transactions, payments and booking systems.
• OLTP is all about data processing, and completing large numbers of small transactions in real-time.

Online Analytics Processing (OLAP):

• Processes complex queries to analyze historical data, e.g. analyzing net profit figures from the past 3 years and sales forecasting.
• OLAP is all about data analysis using large amounts of data and complex queries that take a long time to complete.

Question 3

List 6 different types of databases supported by the AWS ecosystem?

Answer 3

• RDS
• Aurora
• DynamoDB
• DocumentDB
• ElastiCache
• Neptune

Question 4

What is Amazon Relational Database Service (RDS)?

Answer 4

RDS is a service that makes it easy to launch and manage relational databases.

• Supports popular database engines
• Offers high availability and fault tolerance using Multi-AZ deployment option
• AWS manages the database with automatic software patching, automated backups, operating system maintenance, and more.
• Amazon RDS Read Replicas provide enhanced performance and durability for RDS database (DB) instances. They make it easy to elastically scale out beyond the capacity constraints of a single DB instance for read-heavy database workloads.

Question 5

What is Amazon Aurora?

Answer 5

Aurora is a relational database compatible with MySQL and PostgreSQL that was created by AWS.

• Supports MySQL and PostgreSQL database engines
• 5x faster than normal MySQL and 3x faster than normal PostgreSQL
• Scales automatically while providing durability and high availability
• Managed by RDS

Question 6

What is Multi-AZ?

Answer 6

• It’s an exact copy of your production database in another Availability Zone.
• AWS handles the replication for you.
• Multi-AZ is used for Data recovery
• Multi-AZ not for improving performance.
• You cannot connect to the Standby when the Primary DB is active.
• Which databases can be configured as Multi-AZ:
  
  • SQL Server
  • Oracle
  • MySQL
  • PostgreSQL
  • MariaDB

Question 7

What is a Read Replica?

Answer 7

• A Read Replica is a read-only copy of the primary database.
• A Read Replica can be located at the same availability zone
• A Read Replica can be Cross-AZ, located in a different availability zone.
• A Read Replica can be cross region, located in a different region.
• A Read Replica can be promoted to be their own databases. This however breaks the replication.
• Read Replica is used for scaling read perfomance, not for DR
• Requires automatic backup: Automatic backups must be enabled in order to deploy a read replica.
• Multiple Read Replicas are supported; MySQL, Oracle, MariaDB,PostgreSQL and SQL server allow you to add up to 5 read replicas to each DB instance.

Question 8

What are the two types of Backups supported by RDS?

Answer 8

• Database Snapshot:
  
  • Manual,ad-hoc and user-initiated.
  • It provides a snapshot of the storage volume attached to the DB instance
• Automated Backup:
  
  • Enabled by default
  • It creates daily backups or snapshots that run during a backup window that you define.

Question 9

RDS Automated Backups Features?

Answer 9

• Point-In-Time Recovery
  
  • Recover your database to any point in time within a “retention period” of 1-35 days.
• Full daily Backup
  
  • RDS takes a full daily backup, or snapshot, and also stores transactions logs throughout the day.
• The recovery Process
  
  • When you do a recovery, AWS will first choose the most recent daily backup and then apply transaction logs relevant to that day, up to the recovery point.
• Stored in S3
  
  • Automated backups and snapshots are stored in s3
• Free Storage
  
  • You get free storage space equal to the size of your database. So if you have an RDS instance of 10GB, you will get 10GB orth of storage.

Question 10

RDS Encryption at Rest?

Answer 10

• Enable encryption at creation time by selecting the encryption option in the console.
• Encyrption is done using AWS Key Management Service (KMS) AES-256 encryption
• Encryption is applied to all underlying storage, auotmated backups,snapshots,logs, and read replicas.
• Encryption cannot be applied to an unencrypted RDS DB instance. (Must be done at creation)
• Creating an encrypted database from an unencrypted RDS instance
  
  • Take a snapshot (uncrypted)
  • Encrypt snapshot
  • Restore DB from encrypted snapshot