Lemnisk Data Engineer Interview Questions and Answers

Q1. What are synthetic Events?
Ans. 
Synthetic Events are events that are created by the browser to mimic real user events.
• Synthetic Events are used in React to handle events in a consistent manner across different browsers.

• They are created by React to wrap native browser events and provide additional functionality.

• Examples include onClick, onChange, and onSubmit events in React.
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Q2. What is event bubbling?
Ans. 
Event bubbling is the process where an event triggered on a child element is propagated up through its parent elements.
• Event bubbling allows a single event handler to be attached to a parent element, which will be triggered for all its children.

• When an event occurs on a child element, it first runs the event handlers on the child, then on its parent, and so on up the DOM tree.

• Event bubbling can be stopped using event.s
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Q1. What is invoke controller?
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Q2. What is facade in laravel?
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Q1. Difference between union and union all in SQL?
Ans. 
Union combines and removes duplicates, Union All combines without removing duplicates.
• Union combines result sets and removes duplicates

• Union All combines result sets without removing duplicates

• Union is slower than Union All as it involves removing duplicates

• Example: SELECT column1 FROM table1 UNION SELECT column1 FROM table2;

• Example: SELECT column1 FROM table1 UNION ALL SELECT column1 FROM table2;
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Q2. How to show top 5 in pandas?
Ans. 
To show top 5 in pandas, use the nlargest() function.
• Use the nlargest() function with the 'n' parameter set to 5 to get the top 5 values in a pandas DataFrame.

• For example: df['column_name'].nlargest(5) will return the top 5 values in the specified column.
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Q1. If we have 3 numerical columns, which chart is a better representation these column?
Ans. 
A scatter plot is a better representation for 3 numerical columns.
• Use a scatter plot to show the relationship between the numerical columns.

• Scatter plots are effective for visualizing correlations and patterns in data.

• Each point on the plot represents a data point with values from all 3 columns.
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Easy leetcode data structure question

Q1. Write working code for calling a rest API, design rate limiter
Ans. 
Code for calling a REST API and designing a rate limiter
• Use a library like requests or axios to make the API call

• Implement a token bucket algorithm for rate limiting

• Set a maximum number of requests per second and queue excess requests

• Consider using a distributed rate limiter for scalability
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Q1. Design Database schema for instagram
Ans. 
Design a database schema for Instagram.
• Create tables for users, posts, comments, likes, and follows.

• Use primary and foreign keys to establish relationships between tables.

• Store user data such as username, email, and password securely.

• Include fields for post content, location, and timestamp.

• Track likes and comments on posts.

• Implement a notification system for follows and likes.

• Consider scalability and performance in the...read more
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Basic dsa question in python and data engineering questions ,sql

Basic dsa question in python and data engineering questions

Q1. Salary negotiation
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Q1. Questions on vlook up, h-look up, pivot and if else condition
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Q2. You must know how to use vlook up, h-look up and if-else condition
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Excel file was give, used sumifs, countifs , index match formulas

Q1. Ledger details posting profile
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Q2. Fixed Asset project management and accounting
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