Nick’s previously held Software & Data roles at Facebook, Google, & SafeGraph (a geospatial analytics startup).
Currently, he’s the best-selling author of Ace the Data Science Interview, and Founder & CEO of DataLemur.
Nick’s also active on LinkedIn, where he shares career tips with his 160,000+ followers.
At Confluent, their own SQL dialect, KSQL, is often used to look at streaming data from Kafka pipelines in real time. Because of this, Confluent often asks SQL query questions in job interviews for Data Science, Data Engineering, and Data Analytics.
This blog post has 10 questions about the Confluent SQL interview that will help you prepare. Can you answer them all?
Getting hired at a top tech company like Confluent is no easy feat. With its innovative real-time data streaming platform taking the industry by storm, Confluent only recruits the best of the best.
Confluent is a big name in data management, so their interviews are usually tough. They test your knowledge on a lot of technical and soft skills. To stand out from the other applicants and get your dream role, you need to prepare.
In this comprehensive guide, I’ll be sharing the top 15 Confluent interview questions – from Kafka architecture to sales strategies – to help you crush your upcoming interview and join the Confluent team!
Overview of the Confluent Hiring Process
While interviews patterns may vary across roles here’s a general overview of what to expect
-
Initial Screening: A short 30 minute call focused on your resume and experience. Helps filter candidates.
-
Technical Assessment For engineering roles an online coding test to gauge programming abilities.
-
Tech Interview: Live technical interview diving deep into your coding skills and problem solving.
-
Manager Interview: A behavioral interview assessing soft skills like communication, collaboration and culture fit.
-
Executive Interview: Final interview with senior management or engineering leaders. More technical and leadership-focused.
I’ll be covering both technical and non-technical questions to help you ace every step and land the job!
Top 5 Technical Confluent Interview Questions
Let’s start with some of the most common technical questions asked at Confluent:
1. How would you design a scalable and fault tolerant messaging system like Kafka?
This tests your software architecture and distributed systems knowledge – core competencies for working at Confluent.
Your approach should cover:
-
Leveraging partitioning, replication, and distributed commit logs for scalability and fault tolerance.
-
Maintaining message delivery guarantees like at-least-once or exactly-once semantics.
-
Optimizing for performance – minimizing latency and network overhead.
-
Reliable message delivery even during network failures or crashes.
-
Graceful handling of unavailable nodes or consumers to prevent data loss.
-
Effective load balancing and horizontal scaling capabilities.
-
No single point of failures.
Drawing from real-world experience designing such large-scale systems is a huge plus!
2. How is Kafka different from traditional message queues?
This evaluates your knowledge of the core Kafka architecture and its advantages over legacy alternatives like RabbitMQ or ActiveMQ.
Key points to mention:
-
Kafka combines messaging, storage, and stream processing in one system.
-
Offers replayable logs and retention of data for longer periods.
-
Superior throughput, scalability, and fault tolerance compared to traditional message brokers.
-
Pub-sub semantics compared to point-to-point queues.
-
Distributed and horizontally scalable architecture.
-
Build for high performance even with very large data volumes.
3. Explain Kafka topic partitioning and replication.
Since partitioning and replication are fundamental to Kafka’s scalability and availability, this is commonly asked.
Cover the following:
-
Topics are divided into partitions for scalability. Partitions are distributed across cluster.
-
Partitions allow parallelism by having consumer groups read from multiple partitions simultaneously.
-
Replication provides fault tolerance by having each partition replicated across multiple brokers.
-
One broker is the leader, others are followers. All reads/writes go to leader.
-
If leader fails, one of the followers automatically becomes the new leader.
-
Replication ensures smooth failover without any data loss.
4. How does Kafka achieve high performance and low latency?
Kafka’s speed sets it apart, so be ready to discuss its performance optimization techniques:
-
Sequential disk I/O and batching to maximize throughput.
-
Zero-copy design avoids unnecessary data copies.
-
Compression to reduce network bandwidth utilization.
-
Consumer caching and read-ahead fetching to minimize round trips.
-
Request pipelining to allow parallel requests.
-
Mutable batched messages for efficiency.
-
Persistent connections and boostrap lists for fast producer connection.
-
Minimal metadata transfer during failover for availability.
-
Zero-downtime rolling upgrades with no client impact.
5. How would you monitor Kafka performance and troubleshoot issues?
Performance monitoring is critical for running Kafka smoothly in production:
-
Monitor broker-level metrics like CPU usage, JVM heap, I/O rate and network utilization.
-
Track key producer/consumer metrics like request rate, message size, compression rate.
-
Monitor ZooKeeper for contention or failures.
-
Use request latencies to isolate bottlenecks.
-
Analyze consumer lag to detect catch-up issues.
-
Increase log verbosity or enable debug logging for issue diagnosis.
-
Use tcpdump or Wireshark for granular network-level debugging.
-
Leverage Confluent tools like Control Center for visibility into the entire cluster.
Top 5 Non-Technical Confluent Interview Questions
Now let’s look at some common behavioral and role-specific questions:
6. Tell me about a time you successfully explained a complex technical concept to a non-technical audience.
As a tech leader, you need to communicate complex ideas simply. Share an example that demonstrates this ability.
I recently had to explain our scalable messaging architecture to senior executives without technical backgrounds. I used analogies like package delivery tracking and restaurant order fulfillment to convey concepts like message brokers, topics, and producer/consumer flows. The executives not only understood the concepts but were able to have an insightful discussion around business applications.
7. How would you go about identifying potential enterprise customers for Confluent?
Showcase your sales strategy and ability to understand customer needs:
-
Research industries with fast data growth like banking, retail, and logistics.
-
Look for companies modernizing legacy systems or adopting cloud infrastructure.
-
Identify tools/systems used to determine fit for Confluent.
-
Check for engineering teams managing complex data pipelines.
-
Determine tech budget and decision making structure.
-
Reach out to validate pain points and value prop.
The goal is profiling organizations likely to benefit from Confluent to create promising sales pipeline.
8. Tell me about a time you drove collaboration between engineering and business teams.
Managing collaboration across functions is key in leadership roles:
As a product manager, I had to work closely with sales teams to communicate new features to customers, and engineering teams to prioritize functionality based on customer needs.
I fostered collaboration through regular syncs, clear documentation, and keeping all teams updated on major milestones. This ensured both business and technical considerations were incorporated into product roadmaps, accelerating delivery and adoption.
9. How do you motivate your team during stressful situations or tight deadlines?
This tests your people management abilities in high pressure environments:
Open and transparent communication is key. I provide context on why the deadline or scenario is critical for the company’s success. I then work closely with the team to break down complex projects into achievable milestones and build contingency buffers into schedules.
During crunch times, I lead by example putting in extra hours while also ordering food, allowing remote work and encouraging use of PTO to recharge. I find recognizing strong efforts and celebrating wins, even small ones, further motivates teams through challenging periods.
10. Why do you want to work at Confluent in particular?
Conclude with your motivation for joining the company:
I’ve been incredibly impressed by Confluent’s market leadership in leveraging real-time data streaming to transform business. After researching the company, I’m further inspired by the engineering culture focused on creativity, innovation and collaboration.
I strongly believe in Confluent’s vision of enabling enterprises to harness data in motion. I’m excited by the opportunity to contribute to this cutting-edge technology alongside a talented team and help bring game-changing solutions to customers worldwide. This is an unmatched opportunity to grow both professionally and personally.
Putting it All Together
Preparing strong, structured responses for both technical and non-technical questions is the key to interview success at innovative companies like Confluent.
Use this list of 15 top questions with sample answers as a framework to guide your preparation. Tailor your responses using relevant projects and skills from your own background.
With diligent practice, you’ll be able to tackle anything thrown your way. You’ll be leveraging data in motion at Confluent before you know it!
SQL Question 8: Calculate the Average Stream Duration per User for Each Topic
Confluent Inc. is a company that provides a real-time data streaming platform. In this case, let’s say that users are streaming different topics. We want to know how long each user usually streams each topic (in minutes).
We have two tables and .
| topic_id | topic_name |
|---|---|
| 900 | Machine Learning |
| 901 | Database Management |
| 902 | Data Science |
| stream_id | user_id | topic_id | start_time | end_time |
|---|---|---|---|---|
| 6652 | 201 | 900 | 07/01/2022 8:30:00 | 07/01/2022 9:30:00 |
| 5748 | 212 | 900 | 07/01/2022 10:30:00 | 07/01/2022 12:00:00 |
| 4891 | 245 | 902 | 07/02/2022 14:00:00 | 07/02/2022 15:15:00 |
| 7634 | 212 | 901 | 07/03/2022 09:30:00 | 07/03/2022 11:15:00 |
| 8392 | 201 | 902 | 07/04/2022 10:00:00 | 07/04/2022 10:45:00 |
Our goal is to output the following table:
| user_id | topic_name | average_streaming_duration_minutes |
|---|---|---|
| 201 | Machine Learning | 60.00 |
| 212 | Machine Learning | 90.00 |
| 245 | Data Science | 75.00 |
| 212 | Database Management | 105.00 |
| 201 | Data Science | 45.00 |
This query first joins the table with the table on . For each combination of and (from the topics table), the query finds the average difference between and (which tells us how long the stream will last) and divides that number by 60 to get the number of minutes. The clause breaks down this average calculation per user for each topic.
10 Confluent SQL Interview Questions
A platform for streaming real-time data called Confluent wants to find its most active users based on how often events are handled. These are considered “whale users”, or those who perform key activities significantly more than their counterparts. You need to write an SQL query that lists these key users and the total number of events they handled.
The table is formatted as follows:
| event_id | user_id | processed_date | event_type | processed_count |
|---|---|---|---|---|
| 1001 | 762 | 06/08/2022 00:00:00 | Update | 40 |
| 1002 | 543 | 06/10/2022 00:00:00 | Insert | 52 |
| 1003 | 324 | 06/18/2022 00:00:00 | Delete | 35 |
| 1004 | 762 | 07/26/2022 00:00:00 | Update | 60 |
| 1005 | 981 | 07/05/2022 00:00:00 | Update | 43 |
We think the best users are the ones who have handled more than 50 events in a single day.
All records are grouped by the, and the maximum for each user is added up. Only users whose maximum on any given day is more than 50 are then chosen. The result gives the and total number of events processed ( ) for all top users of Confluent.
Try this Microsoft SQL Interview problem to get ready for a similar VIP customer analysis question on DataLemurs’ free online SQL code editor:
What is Confluent | Jay Kreps (CEO, Confluent)
FAQ
Why are you interested in this role with Confluent?
How long does it take to hear back from Confluent?
What are the three types of interviews basic questions?
What is the hiring process at confluent?
The hiring process at Confluent involves submitting an application, reviewing resumes, a phone screening, an initial interview, a technical assessment, a second interview, behavioral assessments, and a final decision. A typical interview process Is it hard to get hired at Confluent? How long does it take to get hired at Confluent?
What is the interview process like at confluent?
I interviewed at Confluent The hiring process at Confluent involves submitting an application, reviewing resumes, a phone screening, an initial interview, a technical assessment, a second interview, behavioral assessments, and a final decision. A typical interview process
What happened at the interview at confluent?
At the end of the interview he gave me an assignment to send him a message on LinkedIn with a few various things about Confluent. He responded asking if I had used ChatGPT. The guy was a giant red flag and completely put me off from wanting to work there. I applied online. I interviewed at Confluent
What is confluent and how does it work?
Confluent is an enterprise-ready, full-scale streaming platform that enhances Apache Kafka. Confluent is a more complete distribution of Kafka in that it enhances the integration possibilities of Kafka by introducing tools for managing and optimizing Kafka clusters while providing methods for making sure the streams are secure.
