database Flashcards
6 Relational databases on AWS
Oracle, SQL server, mysql, postgressql, Amazon aurora, Maria DB
RDS has two key features
Multi AZ - for disaster recovery
Read replicas for performance
Non relational database
Collection is a table
Inside a collection is a document which is a row
Key value paris = fields ( columns)
What is data warehousing
It is used for business analysis
OLTP vs OLAP
OLTP - find a specific order in database
OLAP - Netprofit for America compared to Asia
Redshift
Amazon Data warehousing solution
Elastic cache support two in memory open source cache engines
REDIS and memcached
RDS instance
you cannot patch the RDS instance. RDS is not serverless. Exception is Auroro . Aurora is serverless
Automated backups
Recover to any point in time within the rententioin period. Retention period is between one and 35 days.
Automated backups method
Full snapshot + transactions logs throughout the day.
This allows you to do a point in time recovery down to a second within the rentention period.
Automated backup s3 storage
is free and is equal to the size of the RDS DB
Backup scheduling
Taken during backup window, storage io may be suspended. May experience elevated latency
Restore will restore to a brand new RDS isntance
will result in a different end point
Data at rest is encrypted
Encryption uses KMS service
Multi-AZ
is for disaster recovery only. It is not for improving performance.
Multi AZ is available for
SQL server, Oracle, MySQL, postgres, MariaDB
Read replicase are available for
MySQL, Postgres, mariaDB, Oracle, Aurora
Read replica characteristics
Used for performance not for DR, You must have automatic backup enabled to have read replicas, Upto 5 read replicas. You can have read replicas of read replicas.
Read replica characteristics2
Read replicase with multi-AZ turned on,
You can have read replicase of Multi-AZ source DB
RR can be promoted to its own DB. This breaks replication
You can have read replica in a second region
What do you have to type to delete a RDS
delete me
Dynamo DB
is a no-sql database for apps that need consistent single digit millisecond latency at any scale
Dynamo DB data models
both document and key-value data modesl
Dynamo DB characteristics
stored on SSD, spread across 3 different geographically distinct data centers
Read consistency types
Eventual consistent reads after 1second, strongly consistent reads
Read consistency types
Eventual consistent reads after 1second, strongly consistent reads
Redshift
fully managed petabyte scale db service. $.25 per hour with no commitments. $1000 per TB per year
Redshift can be configured as
Single node(160Gb), Multi-node( Leadernode and Compute node)
Redshift backups
Enabled by default with 1 day retention period
Max retention period=35 days
3 copies, Original, on compute nodes, S3
It can async replicate your snapshots to S3 in another region.
Redshift pricing
compute node hours . 1Unit per node per hour,
Backup
Data transfer ( only within a VPC, not outside)
Redshift pricing
compute node hours . 1Unit per node per hour,
Backup
Data transfer ( only within a VPC, not outside)
Redshift availability
Currently only available in 1AZ
Can restore snapshot to new AZ for DR
Amazon Aurora
MySQL compatible RDB. provides speed and availability of commercial DB and cost effectiveness of open source DB.
Aurora price
1/10 of a commercial DB
Aurora performance
5 times better performance than MySQL. Built by Amaxon from scratch.
Basics of Aurora
Start with 10GB and scales in 10GB increments upto 64TB
Compute resources for Aurora
Can scale up to 32vCPUS and 256Gig memory
Aurora availability
2 copies of data in each AZ, with a min of 3AZ, 6 copies of your data. It is not availabilty in all regions yet
Scaling Aurora
Can handle loss of 2 copies of data without affecting write availability and can handle 3 losses without affecting read availability
Aurora data blocks
self healing . repeatedly scanned and repaired automatically
Auroro replicas
Aurora replicas(currently 15) , MySQL read replicase(currently 5)
Backups with Aurora
Automated backup is always enabled. Backups do not impact performance.
Snapshots with Aurora
This also does not impact performance and you can share snapshots with other AWS accounts.
Aurora nodes
Writer node and reader nodes are created in different AZ. It has a different DNS endpoints
Elasticcache
webserivce that makes it easy to deploy operate and scale in-memory cache.
Redis vs Memcached
Advanced data types, sorting data sets, pub sub capabilities, persistence, Multi-AZ, backup and restore
2 types of RDS backsups
Automated backups and snapshots
Only RDS which does not support read replica
SQL Server
Amazon RDS Provisioned IOPS storage with a Microsoft SQL Server database engine, what is the maximum size RDS volume you can have by default
16 TB
How many copies of my data does RDS - Aurora store by default
6
When you add a rule to an RDS DB security group
Technically a destination port number is needed, however with a DB security group the RDS instance port number is automatically applied to the RDS DB Security Group
Which of the following data formats does Amazon Athena support
“JSON”, “Apache Parquet”, “Apache ORC” amongst others, but “XML” is not a format that is supported.
Redshift is relational or not
relational supports OLAP
You are hosting a MySQL database on the root volume of an EC2 instance. The database is using a large number of IOPS, and you need to increase the number of IOPS available to it. What should you do
Add 4 additional EBS SSD volumes and create a RAID 10 using these volumes.
What happens to the I/O operations of a single-AZ RDS instance during a database snapshot or backup
I/O may be briefly suspended while the backup process initializes (typically under a few seconds), and you may experience a brief period of elevated latency.
What data transfer charge is incurred when replicating data from your primary RDS instance to your secondary RDS instance
no charge
DynamoDB availability
DynamoDB only being single availability zone by default making this the correct answer
DynamoDB primary key
can either be a single-attribute or a composite, user-defined primary key is allowed too
Provisioned IOPS
Provisioned IOPS becomes important when you are running production environments requiring rapid responses, such as those which run e-commerce websites. Without high performant responses from an RDS instance page loads of the website could suffer resulting in loss of business. If your workloads are not latency sensitive or you are running a test environment the additional cost of provisioned IOPS will not be cost beneficial to your project.
In RDS, changes to the backup window take effect
Immediately
In RDS, what is the maximum value I can set for my backup retention period
35 days
Which of the following DynamoDB features are chargeable, when using a single region
There will always be a charge for provisioning read and write capacity and the storage of data within DynamoDB, therefore these two answers are correct. There is no charge for the transfer of data into DynamoDB, providing you stay within a single region (if you cross regions, you will be charged at both ends of the transfer.) There is no charge for the actual number of tables you can create in DynamoDB, providing the RCU and WCU are set to 0, however in practice you cannot set this to anything less than 1 so there always be a nominal fee associated with each table. Further information: https://aws.amazon.com/dynamodb/pricing/
