Tuesday, 23 November 2021

Top 20 AWS Database Interview Questions & Answers

  

Ques: 1). What are your thoughts on the Amazon Database?

Answer: 

Amazon Database is an Amazon Web Services offering that includes managed databases, managed services, and NoSQL. It also comes with a fully managed petabyte-scale data warehouse and in-memory caching as a service. There are four AWS database services to choose from, and the user can use one or all of them depending on their needs. DynamoDB, RDS, RedShift, and ElastiCache are the Amazon database services.

 

Ques: 2). What are the features of Amazon Database?

Answer: 

Following are the important features of Amazon Database:

  • Easy to administer
  • Highly scalable
  • Durable and reliable
  • Faster performance
  • Highly available
  • More secure
  • Cost-effective

 

 Ques: 3). What is a key-value store, and how does it work?

Answer: 

A key-value store is a database service that makes it easier to store, update, and query items that are identified by their keys and values. These objects are made up of keys and values that make up the actual content that is saved.

 

Ques: 4).  What Is A Data Warehouse, And How Can Amazon Redshift Help With Storage?

Answer: 

A data warehouse can be conceived of as a repository for data acquired and stored from the company's systems and other sources. As a result, a data warehouse's design is three-tiered:

The tools that clean and collect data are found on the bottom rung.

We have tools in the intermediate layer that use Online Analytical Processing Server to alter the data.

We have various tools on the top layer that execute data analysis and data mining on the front end.

Setting up and maintaining a data warehouse costs a lot of money, especially as an organization's data grows and its data storage servers need to be upgraded on a regular basis. As a result, AWS RedShift was created, allowing businesses to store their data in Amazon's cloud-based warehouses.

 

Ques: 5). What Is The Difference Between A Leader Node And A Compute Node?

Answer: 

The queries from the client application are received in a leader node, where they are parsed and an execution plan is created. The stages for processing these queries are created, and the outcome is returned to the client application.

The steps allocated in the leader node are completed in a compute node, and the data is transferred. After that, the result is returned to the leader node before being delivered to the client application.

 

Ques: 6). What Is Amazon ElastiCache, and How Does It Work?

Answer: 

Amazon ElastiCache is an in-memory key-value store that can handle Redis and Memcached as key-value engines. It is a fully managed and zero administration service that Amazon has hardened. You may use Amazon ElastiCache to either create a new high-performance application or upgrade an existing one. ElastiCache has a wide range of applications in gaming, healthcare, and other fields.

 

Ques: 7). What Is Amazon ElastiCache's Purpose?

Answer: 

The caching of information that is utilised repeatedly could increase the performance of online applications. Using in-memory-caching, the data may be accessed very quickly. There is no need to manage a separate caching server with ElastiCache. An open source compatible in-memory data source with high throughput and low latency can be readily deployed or run.

 

Ques: 8). When would I prefer Provisioned IOPS over Standard RDS storage?

Answer: 

Provisioned IOPS deliver high IO rates but on the other hand it is expensive as well. Batch processing workloads do not require manual intervention they enable full utilization of systems, therefore a provisioned IOPS will be preferred for batch oriented workload.

 

Ques: 9). What Oracle features are available in AWS RDS?

Answer: 

Oracle is a well-known relational database that is available through Amazon RDS with enterprise version features. Almost every Oracle functionality may be used with the RDS platform.

If no version is specified when the database is created, it defaults to the most recent version available at the moment. In a Python SDK programme, here's an example of how to access the supported DB Engine versions using the AWS API.

 

Ques: 10). What are the differences between Amazon RDS, DynamoDB, and Redshift?

Answer: 

Amazon RDS is a relational database management service that handles patching, upgrading, and data backups for you without requiring your involvement. RDS is a database management service that exclusively handles structured data.

On the other hand, DynamoDB is a NoSQL database service, which works with unstructured data.

Redshift is a data warehouse product that is utilised in data analysis and is a completely different service.

 

Ques: 11). Can I use Amazon RDS to operate many database instances for free?

Answer: 

Yes. You can operate many Single-AZ Micro database instances, and they're all free! Any use of more than 750 instance hours across all Amazon RDS Single-AZ Micro DB instances, across all qualifying database engines and locations, will be paid at normal Amazon RDS charges. For example, if you run two Single-AZ Micro DB instances for 400 hours each in a month, you'll have 800 instance hours total, with 750 hours being free. The remaining 50 hours will be charged at the usual Amazon RDS rate.

 

Ques: 12). What is Oracle Licensing and how does it work?

Answer: 

Oracle licenses can be used in RDS in two ways:

Model with a License

The license for the software you'll use is held by Amazon in this model. Also, through its support programme, AWS provides support for both AWS and Oracle products. As a result, the user does not need to purchase a separate license. The user's licensing costs are included in the platform pricing.

Bring Your Own license

In this arrangement, the user imports her license into the RDS platform. It is the user's responsibility to keep the license, database instance class, and database edition all in sync. The user directly contacts the Oracle support channel for any need. In this model the supported editions are Enterprise Edition (EE), Standard Edition (SE), Standard Edition One (SE1) and Standard Edition Two (SE2).

 

Ques: 13). If I delete my DB Instance, what happens to my backups and DB Snapshots?

Answer: 

When you delete a database instance, you have the option of creating a final database snapshot, which you can use to restore your database. After the instance is removed, RDS keeps this user-made DB snapshot together with all other manually created DB snapshots. Automated backups are also deleted, leaving just manually created DB Snapshots.

 

Ques: 14).  How can I load data into Amazon Redshift from various data sources such as Amazon RDS, Amazon DynamoDB, and Amazon EC2?

Answer: 

You have two options for loading the data:

The COPY command can be used to load data into Amazon Redshift in parallel from Amazon EMR, Amazon DynamoDB, or any SSH-enabled server.

AWS Data Pipeline is a fault-tolerant, high-performance solution for loading data from a range of AWS data sources. To load your data into Amazon Redshift, you can utilise AWS Data Pipeline to specify the data source, required data transformations, and then run a pre-written import script.

 

Ques: 15). What is an RDS instance, and how does it work?

Answer: 

The Amazon Relational Database Service (Amazon RDS) is a web service that lets you easily construct a cloud-based relational database instance. Amazon RDS administers the database instance on your behalf, including backups, failover, and database software maintenance. Read Replicas, which are RDS instances that act as copies of the source master database for handling read-requests, can be launched for read-heavy applications. A source DB instance can have up to five (5) Read Replicas attached to it. The existing RDS Instances in the selected AWS region are listed on the Instances page. The information for an existing RDS Instance are displayed when you click on it.

Fields

Name - unique name/identifier for the RDS instance.

Engine - The version of the MySQL or Oracle engine of the RDS Instance.

RDS Subnet Group - The group of RDS Subnets for the VPC.

Availability Zone - The availability zone into which the RDS Instance will be created and launched.

Multi-AZ - Indicates that the RDS Instance will be used in a multiple availability zone configuration.

Instance class - If you selected a different instance type, the existing instance will be terminated and new RDS instance will be launched.

Storage - storage size in GBs for the instance that will be allocated for storing data.

Source instance - If the instance is a Read Replica, it will list the name of the source DB instance.

Status - The status of the RDS Instance (creating, modifying, available, rebooting, deleting). An RDS Instance will only be accessible when its status is 'available'.

 

 

Ques: 16). What is Amazon Aurora and how does it work?

Answer: 

Amazon Aurora is a form of cloud-based relational database that works with MySQL and PostgreSQL. It performs five times faster than MySQL and three times faster than PostgreSQL. The performance and availability of traditional databases are combined with the simplicity and cost-effectiveness of open-source databases in this hybrid database type. Because Amazon RDS manages this database completely, operations like hardware provisioning, database setup, patching, and backups are all automated.

 

Ques: 17). Which Amazon Web Services services will you use to collect and process e-commerce data in real time for analysis?

Answer: 

For real-time analysis, I'll utilise DynamoDB to collect and handle e-commerce data. DynamoDB is a fully managed NoSQL database service for unstructured data. It can even be used to extract e-commerce information from websites. RedShift may then be used to perform analysis on the retrieved e-commerce data. Elastic MapReduce can be utilised for analysis as well, but we won't use it here because real-time analysis isn't required.

 

Ques: 18). What happens if a user deletes a dB instance? What happens to the dB snapshots and backups?

Answer: 

The user is given the option of taking a last dB snapshot when a dB instance is removed. If you do so, your information from the snapshot will be restored. When the dB instance is removed, AWS RDS preserves all of the user-made dB snapshots together with all of the other manually created dB snapshots. Automated backups are erased at the same time, but manually produced dB snapshots are kept.

 

Ques: 19). What Is A Dynamodbmapper Class And How Does It Work?

Answer: 

The DynamoDB's entry point is the mapper class. It allows users to access the endpoint and input the DynamoDB. Users can use the DynamoDB mapper class to retrieve data stored in various databases, run queries, scan them against the tables, and perform CRUD activities on the data items.

 

Ques: 20). What is the RDS interface, and how does it work?

Answer: 

To use the RDS service, Amazon provides an RDS interface. An RDS interface is required to interact with the RDS service, such as reading data, uploading data, and running other programmes.

The GUI Console, Command Line Interface, and AWS API are the three main interfaces available.

A GUI Console is the most basic interface via which users can interact with the RDS Service.

The Command Line Interface (CLI) provides you with CLI access to the service, allowing you to run DB commands and interact with it.

An AWS API is an Application Programming Interface that allows two systems to exchange data.