Featured Post

Python Set Operations Explained: From Theory to Real-Time Applications

-
Image
A  set  in Python is an unordered collection of unique elements. It is useful when storing distinct values and performing operations like union, intersection, or difference. Real-Time Example: Removing Duplicate Customer Emails in a Marketing Campaign Imagine you are working on an email marketing campaign for your company. You have a list of customer emails, but some are duplicated. Using a set , you can remove duplicates efficiently before sending emails. Code Example: # List of customer emails (some duplicates) customer_emails = [ "alice@example.com" , "bob@example.com" , "charlie@example.com" , "alice@example.com" , "david@example.com" , "bob@example.com" ] # Convert list to a set to remove duplicates unique_emails = set (customer_emails) # Convert back to a list (if needed) unique_email_list = list (unique_emails) # Print the unique emails print ( "Unique customer emails:" , unique_email_list) Ou...
Post a Comment

8 top AWS tricky interview Questions

-
In this post, I have explained AWS (Amazon Web Services) tricky interview questions. The EBS, AMI, S3 and Amazon instance included in my questions

Q1. Explain Elastic Block Storage? What type of performance can you expect? How do you back it up? How do you improve performance?

 A1. EBS is a virtualized SAN or storage area network. That means it is RAID storage to start with so it’s redundant and fault-tolerant. If disks die in that RAID you don’t lose data.

Great! It is also virtualized, so you can provision and allocate storage, and attach it to your server with various API calls. No calling the storage expert and asking him or her to run specialized commands from the hardware vendor.
 
Performance on EBS can exhibit variability. That is it can go above the SLA performance level, then drop below it. The SLA provides you with an average disk I/O rate you can expect.

This can frustrate some folks especially performance experts who expect reliable and consistent disk throughput on a server. Traditional physically hosted servers behave that way. Virtual AWS instances do not.
AWS Interview Questions
AWS Interview Questions
Backup EBS volumes by using the snapshot facility via an API call or via a GUI interface like elastic fox. Improve performance by using Linux software raid and striping across four volumes.
Q2. What is S3? What is it used for? Should encryption be used?
A2. S3 stands for Simple Storage Service. You can think of it like FTP storage, where you can move files to and from there, but not mount it like a file system. 

AWS automatically puts your snapshots there, as well as AMIs there. Encryption should be considered for sensitive data, as S3 is a proprietary technology developed by Amazon themselves, and as yet unproven vis-a-vis a security standpoint.
Q3. What is an AMI? How do I build one?

A3. AMI stands for Amazon Machine Image. It is effectively a snapshot of the root file system. Commodity hardware servers have a BIOS that points the master boot record of the first block on a disk. 
A disk image though can sit anywhere physically on a disk, so Linux can boot from an arbitrary location on the EBS storage network.
Build a new AMI by first spinning up and instance from a trusted AMI. Then adding packages and components as required. Be wary of putting sensitive data onto an AMI. 
For instance, your access credentials should be added to an instance after spinup. With a database, mount an outside volume that holds your MySQL data after spinup as well.
Q4. Can I vertically scale an Amazon instance? How?

 A4. Yes. This is an incredible feature of AWS and cloud virtualization. Spinup a new larger instance than the one you are currently running. Pause that instance and detach the root EBS volume from this server and discard it. 

Then stop your live instance, detach its root volume. Note the unique device ID and attach that root volume to your new server. And then start it again. Voila, you have scaled vertically in-place!! Read online for more questions

Comments

Post a Comment

Thanks for your message. We will get back you.

Popular posts from this blog

SQL Query: 3 Methods for Calculating Cumulative SUM

-
Image
SQL provides various constructs for calculating cumulative sums, offering flexibility and efficiency in data analysis. In this article, we explore three distinct SQL queries that facilitate the computation of cumulative sums. Each query leverages different SQL constructs to achieve the desired outcome, catering to diverse analytical needs and preferences. Using Window Functions (e.g., PostgreSQL, SQL Server, Oracle) SELECT id, value, SUM(value) OVER (ORDER BY id) AS cumulative_sum  FROM your_table; This query uses the SUM() window function with the OVER clause to calculate the cumulative sum of the value column ordered by the id column. Using Subqueries (e.g., MySQL, SQLite): SELECT t1.id, t1.value, SUM(t2.value) AS cumulative_sum FROM your_table t1 JOIN your_table t2 ON t1.id >= t2.id GROUP BY t1.id, t1.value ORDER BY t1.id; This query uses a self-join to calculate the cumulative sum. It joins the table with itself, matching rows where the id in the first table is greater than...
Read more

Big Data: Top Cloud Computing Interview Questions (1 of 4)

-
Image
The below are frequently asked interview questions on Cloud computing: 1) What is the difference between Cloud and Grid? Grid: -Information service -Security Service -Data management -Execution Manageement Cloud: - Maintains up-to-date information of resources -Create VMs according to user requirement -Application deploment -User management 2) What are the different cloud standards? -Interoperability standards -Security standards -Portability Standards -Governance and Risk standards 3) What are the two different sub-systems in Cloud computing ? -Management sub system -Resource sub system 4)What is Cloud compouting? The promise of cloud computing is ubiquitous access to a broad set of applications and services, which are delivered over the network to multiple customer. 5) Why we need specialized network for Cloud services? The public Internet is the simplest choice for delivering cloud-based services. In this model, the cloud provider simply purchases Inter...
Read more

5 SQL Queries That Popularly Used in Data Analysis

-
Image
 Here are five popular SQL queries frequently used in data analysis. 1. SELECT with Aggregations Summarize data by calculating aggregates like counts, sums, averages, etc. SELECT department, COUNT(*) as employee_count, AVG(salary) as average_salary FROM employees GROUP BY department; 2. JOIN Operations  Combine data from multiple tables based on a related column. SELECT e.employee_id, e.name, d.department_name FROM employees e JOIN departments d ON e.department_id = d.department_id; 3. WHERE Clause for Filtering Filter records based on specified conditions. SELECT * FROM sales WHERE sale_date BETWEEN '2024-01-01' AND '2024-12-31'   AND amount > 1000; 4. ORDER BY Clause for Sorting Sort results in ascending or descending order based on one or more columns. SELECT product_name, price FROM products ORDER BY price DESC; 5. GROUP BY with HAVING Clause Group records and apply conditions to the aggregated results. SELECT department, SUM(salary) as total_salaries FROM employ...
Read more