RDS & DynamoDB Flashcards
eventually consistent vs strongly consistent reads
“Strongly consistent returns the most up to date data but may take longer to get >1sec
eventually consistent returns whatever is currently in the system which may not include recent updates”
What is a CNAME used for?
“Canonical Name
Points one domain address to another
often a sub domain (ft.mydomain.com) to it’s main domain(www.mydomain.com)”
What is the failover mechanism feature?
A safety feature that automatically changes the DNS CNAME record of DB instances to point to backup instances in the event of failure
What is Aurora?
“A MySQL and PostreSQL compatible relational database built for the cloud
High performance and availability at 1/10th the cost”
What is provisioned throughput capacity?
“A setting that needs to be configured when creating a DynamoDB
Writes are more expensive than reads
Because of this read heavy applications work well on DynamoDB”
What is a primaryKey in DynamoDB?
“Primary Key is either
Partition key
Partition key and sort key (essentialy a way to improve look up potential)”
What causes DynamoDB to reject requests?
“Tables are aranged poorly so that queries overburden one partition too much
Adaptive capacity is a feature that borrows capacity from other partitions, mitigating poor table design for most cases”
What is the RCU and WCU limits per partition?
“Read capacity units - 3000
Write capacity units - 1000”
In DynamoDB what is a GSI?
“Global Secondary Index
A feature to reduce the use of scan and filerExpression on the data
Allows you to query a table by a row that is not the primary key
GSI clones your primary table using your new Partition Key, but keeps these two tables in sync”
Which database service supports schema changes?
Aurora
What is the Elasticache Service?
Caches all th ecommon queries so data sets will be fetched from the cache rather than the database
Standby vs Read Replica
“uses synchronous replication between primary and standby systems
read replicas use asynchronous replication”
What is Multi-region replication or Global tables?
“AWS managed multi-region, multi-master database
Every region has their own table and AWS ensures that they are synced within 3 seconds
Only enabled on tabels with
no data (empty table)
tables with the same name and structure”
transporting from redshift to S3 within VPC
create and configure S3 VPC endpoint. enable redshift enhanced VPC routing feature.
What is Redshift?
An AWS columnar datastore
What feature creates copies of Redshift in other regions
“Cross-Region Snapshot
copies can be created automatically or manually”
What feature provides enhanced availability an durability for RDS?
“RDS multi-az deployment
Amazon automatically creates a primary DB instance and synchronously replicates the data to a standby instance in a different AZ”
What is DynamoDB streams?
An ordered flow of information about changes to items in a DynamoDB table
process of automated backup of Amazon RDS
“storage volume snapshot of database instance is created once daily
for restoring at a specific point in time best practice is to capture transaction logs every 5 minutes in an S3 bucket”
What Redshift feature ensures all traffic to and from it are within the VPC?
Enhanced VPC routing
