AWS SAA Exam: Database Practice Questions

Can you increase performance by moving from a single instance RDS to a multi-AZ architecture?
No, you can increase performance by creating a read-replica and using it only for reads, while writing to the master instance.
Which of these are not a supported OLTP database type for RDS?
				A. Aurora
				B. MariaDB
				C. SQLite
				D. MySQL
C is correct. SQLite is not supported.
If Redshift is not OLTP, what is it?
Online Analytics Processing (OLAP). OLAP databases are optimized for running huge queries on large datasets. OLAP is the tech powering BI applications. Used for report viewing, analytical calculations, predictive analytics. OLAP databases use a multidimensional data model, allowing for complex analytical and ad hoc queries to run quickly. In contrast to OLTP, it is optimized for less frequent query execution, but larger more complex queries. It is also optimized for READ queries, whereas OLTP is optimized for all types of queries (read, insert, update, and delete).
You need to migrate an on-prem PostreSQL database cluster to AWS. The replication lag must be less than 90 ms for the cluster, and you are expecting the size to triple in 3 months. What type of DB is best?
Aurora is a db cluster with very low replication times and can autoscale from 10 GB (min) to 64 TB (max). Regular RDS does NOT feature ultra-low replication lag for the read replica however multi-AZ RDS is synchronous.
T/F In redshift, backups are enabled by default with a 1 day retention period
Which of these redshift configurations exist? Select two.
				A. Single-Node
				B. Sharded with a master node and replica node
				C. Multi-node with a leader node and compute node
				D. Distributed with a main node and child node
A and C both are correct.
Why is columnar storage optimal for OLAP?
				A. Each data block stores values of multiple rows.  Hence, reading the same number of
				column field values for the same number of records requires less I/O operations compared
				to row-wise storage.
				B. Each data block stores values of multiple columns.  Hence, reading the same number of
				column field values for the same number of records requires less I/O operations compared
				to row-wise storage.
				C. Indexes are added to the columns where they'd normally be added to the rows.
				D. Compression can be optimized for column's data type.
A and D are correct. For more information, see
Which database types are serverless?
				A. DynamoDB
				B. Aurora Serverless
				C. PostgreSLQ Serverless
				D. MariaDB Serverless
A and B are correct.
Which RDS replica type supports automated failover?
				A. Aurora Replicas
				B. MySQL Replicas.
				C. PostgresQL replicas.
A is correct.
T/F RDS Read replicas can be multi-AZ
T/F Multi-AZ is used for increasing performance
False, it is used for DR. Multi-AZ RDS deployments contain a primary instance and a standby instance in another AZ. In case of an infrastructure failure, RDS performs an automatic failover to the stand by so that you can resume database operations as soon the failover is complete. With aurora, read replicas across 3 availability zones and failover is quicker.
T/F once your RDS instance is encrypted, its automated backups, read replicas, and snapshots are encrypted.
T/F dynamo DB is stored on magnetic disk drives and spread across 3 geographically distinct data centers
False, while it is spread across 3 data centers, it uses SSDs rather than magnetic disk drives.
What is the maximum retention period for both RDS and Redshift backups?
35 days
T/F Redshift always tries to keep 3 copies of your data
Which type of Elasticache should you use if you need it to be multi-AZ?
				A. Redis
				B. Memcached
A. Redis is multi-AZ
Which type of Elasticache should you use if you need to scale horizontally?
				A. Redis
				B. Memcached
B. Memcached is multithreaded, so it can handle more operations by scaling up compute capacity.
Which type of Elasticache should you use if you need to take snapshots, do backups and restores?
				A. Redis
				B. Memcached
A. Redis can take snapshots. It also supports replication.
Which can you use with Aurora?
				A. MariaDB
				B. SQL Server
				C. MySQL
				D. PostgreSQL
C and D are correct.
Which Elasticache option should you use if you need AWS native encryption?
				A. Redis
				B. Memcached
A is correct.
What is the size limit of the combined name and value size for a dynamoDB record?
400 KB
T/F For a media site anticipating a spike in traffic for an article, you can resolve high-traffic induced read contentions on RDS by adding elasticache in front to handle static content or add a read replica. These both could be cheaper than the option of scaling up your instance.
T/F DynamoDB is good for storing archive data.
T/F DynamoDB is good for storing BLOB data.
False. Oracle DB is able to store BLOB data.
How long will an RDS Multi-AZ failover take?
The failover takes 1-2 minutes.
T/F A standy RDS instance in a multi-AZ deployment is replicated synchronously or asynchronously?
You have an ASG for instances of an application server that connect to a DB in AWS. Which can be used to alleviate periods of high number of queries on a database such as RDS or DynamoDB?
				A. Enable Multi-AZ
				B. Use Transfer Acceleration
				C. Put Elasticache in front of the DB to cache common queries
				D. If it's dynamoDB, enable auto-scaling
D is true. C could be used depending on the situation if it's acceptable to cache query responses.
You want a NoSQL database that's really easy to use for beginners and highly available, and you're ok if it has a limit on request capacity and storage size for any given table. What should you use?
SimpleDB. DynamoDB has no limit on request capacity or storage size per table and is also highly available.
You want users to only access your MySQL PostgreSQL instance using an authentication token with a 15 minute life instead of a username and password. How can you do this?
				A. Enable MFA tokens for DB access
				B. Enable RDS-PostgreSQL STS token access  using the AWSAuthentiationPlugin
				C. Set up an RDS token in AWS Directory Service
				D. Use IAM DB Authentication and create db accounts using the AWSAuthentiationPlugin in PostgreSQL
D is correct. AWSAuthentiationPlugin is a db plugin available for MySQL and PostgreSQL RDS databases. SSO lets you manage SSO access to AWS accounts across AWS Organizations as well as business services such as Office 365. It is not used for DB Access. MFA is for multi-factor authentication when loggint in to AWS or performing actions such as deleting objects from S3 buckets.
Which of these is NOT true about the Database Migration Service (DMS) and Schema Conversion Tool (SCT)?
				A. It can do heterogenous migrations, e.g. from MySQL to PostgreSQL, or Oracle DB to a NoSQL DynamoDB
				B. During migration, the source database can still be used
				C. DMS can only be used for one-time replication, not ongoing replication.
				D. SCT can be used before DMS to convert the source schema and app code to match target database
C is correct, as this is the untrue anwer. DMS can be used for ongoing replication to keep source and target in-sync. SCT does not support this.