Interviewer (I): Uh, yeah. Uh, can you quickly walk me through your profile?
Candidate (C): Yeah, sure. Thanks for this opportunity. My name is Dinesh. I have a total of four years of experience in IT. Most of my relevant experience comes from working with Power BI, which is almost three years. Currently, I'm employed at Fidelity. This is my current company. I've been involved in many end-to-end reporting projects. As for my skills, I'm proficient in SQL and visualization tools such as Power BI. Much of my experience involves building comprehensive reports. Right now, I'm working with a client named Sigma, a US-based insurance company. This client requires us to gather and analyze insurance data from on-premises databases for reporting purposes.
INTERVIEWER: Great. Can you tell me about the sources you've connected for the current project?
CANDIDATE: Certainly. For the current project at Sigma, we're connected to a Microsoft SQL database using the import mode. Although I have experience with various data sources like CSV, Excel, JSON, and XML files, for this project, we're specifically using a SQL Server.
INTERVIEWER: Could you explain the difference between import mode and direct query mode?
CANDIDATE: Import mode and direct query mode are both ways to access data. In import mode, Power BI brings the data into its environment, allowing for comprehensive modeling, including creating schemas, implementing functions, and more. However, there's a storage limitation. Direct query mode, on the other hand, accesses data from the source tables via queries. It's beneficial when dealing with unlimited data sizes. Import mode lets you build complex models, while direct query mode allows for working with vast datasets directly from the source.
INTERVIEWER: How would you rate your proficiency in SQL and Power BI?
CANDIDATE: In terms of SQL, I'd rate myself at around 3.5 out of 5. As for Power BI, I'd give myself a 4 out of 5. SQL was my starting point, and I've honed my skills with it. With Power BI, I've gained significant experience over time.
INTERVIEWER: Can you share your role and responsibilities across the projects you've worked on as a Power BI developer?
CANDIDATE: Certainly. In my current project, I'm the sole Power BI developer. I've been involved in the entire lifecycle, starting from gathering requirements. Our client provided requirements without direct data, so I had to analyze the database, identify relevant tables, and create schema structures. I've also performed various data transformations, including text, column, and data transformations. I'm well-versed in choosing the appropriate visualization charts for different data. Additionally, I've been responsible for publishing the reports and setting up schedules for automated updates.
INTERVIEWER: Have you worked with any custom charts beyond the default ones?
CANDIDATE: Yes, I have. While custom charts are typically obtained through premium access or organizational accounts, I've used charts like infographic charts, scroller charts for categorical data, word clouds, and drill-down column charts. We follow guidelines to ensure the charts we use are approved and reliable for our reports.
INTERVIEWER: How about Sankey charts or ribbon charts? Are you familiar with those?
CANDIDATE: Certainly. Sankey charts are useful for visualizing relationships between categorical variables. Ribbon charts, on the other hand, are an extended version of stacked column charts. They allow you to visualize the change and growth between different levels, making them great for year-over-year comparisons or percentage growth analyses.
INTERVIEWER: Have you utilized conditional formatting in your reports?
CANDIDATE: Yes, I've implemented conditional formatting, especially when accuracy down to the decimal point is crucial. We use it in metrics and tables to make the data more informative and visually appealing.
INTERVIEWER: You mentioned working with DAX functions. Can you provide an example of a scenario where you used DAX functions?
CANDIDATE: Certainly. Let's say we have a sales scenario, and we want to compare this year's sales with the sales of the previous year for the same time frame, say from November to December. In this case, I'd use the SAMEPERIODLASTYEAR function. It's a versatile way to achieve year-over-year comparisons without having to manually adjust time frames.
INTERVIEWER: Have you also worked with DAX functions beyond this example?
CANDIDATE: Absolutely. I've worked with various DAX functions. For instance, I've used SUMX for calculating totals even when the original column isn't present. It's a powerful way to achieve calculations without altering the original dataset. I've also used RANKX, ALL, ALLSELECTED, and ALLEXCEPT functions, depending on the requirements and context of the reports.
INTERVIEWER: You mentioned working with Power Query Editor for data transformations. Can you share some of the transformations you've performed?
CANDIDATE: Certainly. I've worked with text transformations, number transformations, column transformations, and merging queries. I've also built schema structures like star schemas and snowflake schemas to organize the data efficiently. Power Query Editor has been instrumental in transforming raw data into meaningful insights.
INTERVIEWER: Have you faced any challenges during your projects?
CANDIDATE: Yes, there were a few challenges. One significant challenge was data gathering. Clients often provide requirements without direct data sources, which means I had to explore and identify relevant tables. Additionally, implementing complex calculations and DAX functions sometimes required intensive effort. In another project, data performance tuning was crucial, where we aimed to optimize report performance through efficient Power Query transformations.
INTERVIEWER: Could you provide an example of a complex report you've built and any positive feedback you received?
CANDIDATE: Certainly. In a previous project for a telecommunication vendor, we built a dynamic report with innovative features. One instance was using infographic charts to represent different telecom services visually. The client appreciated the creativity and out-of-the-box thinking, and the report was well-received.
INTERVIEWER: What type of access did you hold in your projects, and what were your roles?
CANDIDATE: In my current project, I held contributor access since I was the primary Power BI developer. I had the responsibility of creating reports, performing data transformations, and publishing them. I've seen different roles in other projects, where teams had multiple members with varying levels of access.
INTERVIEWER: Have you implemented row-level security in your reports?
CANDIDATE: Yes, we've implemented row-level security to restrict data access based on user roles. This ensures that each user sees only the relevant data, enhancing data security.
INTERVIEWER: How do you keep yourself updated with Power BI's frequent updates?
CANDIDATE: I stay updated by regularly checking Microsoft's official documentation, where they summarize new features and updates each month. I also engage in hands-on Proof of Concept (POC) projects to test new features before incorporating them into live projects. For instance, I recently explored small multiples for improved data visualization.
INTERVIEWER: Thank you for sharing your experiences and insights. Do you have any questions for me?
CANDIDATE: Yes, thank you for the discussion. I'd like to know more about the specific role you're looking to fill and the challenges the team is currently facing.
INTERVIEWER: Certainly. We're seeking a Power BI developer with end-to-end experience, similar to what you've described. The role involves working across all phases of the reporting lifecycle, from data gathering to sharing insights with stakeholders. It seems like your experience aligns well with our requirements.
CANDIDATE: Thank you for the information. It's been a great conversation and I appreciate the opportunity to discuss my background and skills.
INTERVIEWER: Likewise, thank you for your time. We'll be in touch soon regarding the next steps in the interview process.
CANDIDATE: Sounds good. Looking forward to it. Thank you again.
INTERVIEWER: You're welcome. Have a great day.
CANDIDATE: You too. Goodbye
