Exusia Software Engineer Interview Guide

The 60-second brief

The role of a Software Engineer at Exusia is pivotal in driving innovative software solutions that meet the complex needs of our clients. As a Software Engineer, you will be part of a collaborative team that focuses on developing and maintaining software applications across various domains, particularly in data management and analytics. Your work will directly impact the quality and efficiency of our products, ensuring that they meet the highest standards of functionality and user satisfaction. In this role, you will engage with cutting-edge technologies and methodologies, contributing to projects that enhance the scalability and performance of our systems. The challenges you will face are both exciting and complex, making this position critical to our mission of delivering exceptional value to our clients.

This guide is scoped to a Software Engineer candidate at Exusia.

Focus areas

• SQL
• Ab Initio
• Python

The Exusia interview process

Exusia candidates report 3 rounds over 3-5 weeks. The stages below are what candidates describe, not a published process.

Technical Screening

Initial assessment to evaluate your technical skills and domain knowledge.

What to demonstrate

• Initial assessment to evaluate your technical skills and domain knowledge
• Depth in SQL

How to prepare

• Answer aloud and timed: Explain the concept of a primary key and a unique key in SQL.
• Answer aloud and timed: How do you optimize SQL queries for performance?

In-Depth Technical Interview

One or two detailed interviews focusing on advanced technical skills.

What to demonstrate

• One or two detailed interviews focusing on advanced technical skills
• Depth in SQL

How to prepare

• Answer aloud and timed: Describe a recent project where you utilized Java. What challenges did you face?
• Answer aloud and timed: Discuss the differences between relational and non-relational databases.

Cultural Fit Interview

Final round discussion to assess alignment with company culture and values.

What to demonstrate

• Final round discussion to assess alignment with company culture and values
• Depth in SQL

How to prepare

• Answer aloud and timed: Can you explain the ACID properties of transactions?
• Answer aloud and timed: Given a dataset, how would you approach analyzing and deriving insights from it?

Where candidates lose points

Practice coding

Regularly solve coding problems on platforms like LeetCode or HackerRank to sharpen your skills.

Be prepared to discuss your resume

You'll likely be asked about projects listed on your resume, so be ready to provide detailed explanations.

Understand the company culture

Familiarize yourself with Exusia’s values and mission to demonstrate alignment during your interviews.

Ask insightful questions

Prepare thoughtful questions to ask your interviewers, showing your genuine interest in the role and the company.

Questions & practice

Write a function to reverse a string in Java.

Medium · Coding / Algorithms

Approach

1. Restate the input: its shape, its size, and what is guaranteed about it.
2. Name the brute-force solution and its complexity before improving on it.
3. Choose the data structure from the access pattern, not from familiarity.
4. State the target complexity and say which constraint rules the naive version out.

Follow-up

• How does this change if the input no longer fits in memory?
• What is the worst case, and how likely is it on real data?

How would you implement a binary search algorithm?

Medium · Coding / Algorithms

Approach

1. Restate the input: its shape, its size, and what is guaranteed about it.
2. Name the brute-force solution and its complexity before improving on it.
3. Choose the data structure from the access pattern, not from familiarity.
4. State the target complexity and say which constraint rules the naive version out.

Follow-up

• How does this change if the input no longer fits in memory?
• What is the worst case, and how likely is it on real data?

Solve a problem involving data structures, such as linked lists or trees.

Medium · Coding / Algorithms

Approach

1. Restate the input: its shape, its size, and what is guaranteed about it.
2. Name the brute-force solution and its complexity before improving on it.
3. Choose the data structure from the access pattern, not from familiarity.
4. State the target complexity and say which constraint rules the naive version out.

Follow-up

• How does this change if the input no longer fits in memory?
• What is the worst case, and how likely is it on real data?

Explain the concept of a primary key and a unique key in SQL.

Medium · Technical / Domain Questions

Approach

1. Name the grain you start from and join outward from it.
2. Check whether any join is one-to-many before aggregating, or the sums inflate.
3. Say which index the query would use, and what makes it unusable.
4. Handle the rows that do not match: that is usually the actual question.

Follow-up

• How does the query change if that join becomes one-to-many?
• What happens to this when the table is ten times larger?

How do you optimize SQL queries for performance?

Medium · Technical / Domain Questions

Approach

1. Name the grain you start from and join outward from it.
2. Check whether any join is one-to-many before aggregating, or the sums inflate.
3. Say which index the query would use, and what makes it unusable.
4. Handle the rows that do not match: that is usually the actual question.

Follow-up

• How does the query change if that join becomes one-to-many?
• What happens to this when the table is ten times larger?

Describe a recent project where you utilized Java. What challenges did you face?

Medium · Technical / Domain Questions

Approach

1. Clarify what is being asked and what a complete answer contains.
2. State your assumptions explicitly before working the problem.
3. Say what you would check first and why it is the highest-information step.
4. Work from the requirement backwards to the design.

Follow-up

• What assumption would you test first?
• How would you know your answer was wrong?

Discuss the differences between relational and non-relational databases.

Medium · Technical / Domain Questions

Approach

1. Clarify what is being asked and what a complete answer contains.
2. State your assumptions explicitly before working the problem.
3. Say what you would check first and why it is the highest-information step.
4. Work from the requirement backwards to the design.

Follow-up

• What assumption would you test first?
• How would you know your answer was wrong?

Can you explain the ACID properties of transactions?

Medium · Technical / Domain Questions

Approach

1. Clarify what is being asked and what a complete answer contains.
2. State your assumptions explicitly before working the problem.
3. Say what you would check first and why it is the highest-information step.
4. Work from the requirement backwards to the design.

Follow-up

• What assumption would you test first?
• How would you know your answer was wrong?

Given a dataset, how would you approach analyzing and deriving insights from it?

Medium · Problem-solving / Case Studies

Approach

1. Clarify what is being asked and what a complete answer contains.
2. State your assumptions explicitly before working the problem.
3. Say what you would check first and why it is the highest-information step.
4. Work from the requirement backwards to the design.

Follow-up

• What assumption would you test first?
• How would you know your answer was wrong?

How would you design an ETL process for a given data source?

Medium · Problem-solving / Case Studies

Approach

1. Fix the scope first: who calls this, how often, and what they do when it fails.
2. Name the read and write paths separately; they rarely have the same bottleneck.
3. Choose a partition key and say what query it makes expensive.
4. State the consistency you need, and where you are willing to be stale.

Follow-up

• What breaks first when traffic grows ten times?
• How does this behave when that dependency is down for an hour?

One log partition stops advancing while the others drain

Easy · poison message · head-of-line blocking · consumer lag

Search results for a subset of tenants are hours stale; the rest are current. The projection consumer reports lag of zero on 15 of 16 partitions and 400,000 on one. Its error rate is flat and its CPU is idle. outbox_event has no pending rows older than a second, so the relay has published everything it holds. Identify the mechanism, give the ordered checks, and state what you do in the first ten minutes versus what you change permanently.

Approach

1. Read the lag distribution first. A slow consumer lags everywhere; zero on fifteen partitions and 400,000 on one is not throughput. Idle CPU on the stuck partition means the consumer is not advancing its offset at all, which points at one message it cannot get past rather than at a rate problem.
2. Exonerate the producer before touching the consumer. No pending outbox rows older than a second means the relay published, so the event exists in the log. This separates never sent from sent and never applied, which are different code paths and usually different owners.
3. Read the message at the stuck offset and the handler's log lines for its event_id. A flat error rate with no progress has two explanations and you must distinguish them: the handler is throwing and the retry loop is swallowing it, or the handler is blocking on something and never returning. Idle CPU with no error lines favours the second.
4. Mitigate before diagnosing further. Move the offending event to a dead-letter store and commit the offset past it. Adding consumers does nothing here, because a partition is consumed by exactly one member of the group, and the blast radius is every aggregate hashed to that partition, not only the aggregate that produced the bad event.

Follow-up

• The dead-lettered event carried aggregate_version 7 and the projection had applied 6. What must the replay do differently if 8 and 9 landed in the meantime?
• How do you show staleness to the user while the partition is behind, given the API already returns the projection's watermark?

Suggested practice checklist

Built from the rounds and topics Exusia candidates report.

Day 1 — Map the Exusia loop

• Write out the reported sequence: Technical Screening, In-Depth Technical Interview, Cultural Fit Interview.
• For each round, write one sentence on what it is judging, from the description above, and mark the one you are least ready for.

Deliverable: A one-page map of the 3 reported rounds, with the weakest marked.

Day 2 — Work SQL

• Spend the session on SQL, which Exusia candidates report being tested on.
• Write one worked example in SQL and time yourself on it.

Deliverable: One timed worked example in SQL.

Day 3 — Work Ab Initio

• Spend the session on Ab Initio, which Exusia candidates report being tested on.
• Write one worked example in Ab Initio and time yourself on it.

Deliverable: One timed worked example in Ab Initio.

Day 4 — Work Python

• Spend the session on Python, which Exusia candidates report being tested on.
• Write one worked example in Python and time yourself on it.

Deliverable: One timed worked example in Python.

Day 5 — Answer out loud: Technical / Domain Questions

• Answer aloud, timed: Explain the concept of a primary key and a unique key in SQL.
• Answer aloud, timed: How do you optimize SQL queries for performance?

Deliverable: Spoken answers to 2 reported Technical / Domain Questions question(s), under time.

Day 6 — Answer out loud: Problem-solving / Case Studies

• Answer aloud, timed: Given a dataset, how would you approach analyzing and deriving insights from it?
• Answer aloud, timed: How would you design an ETL process for a given data source?

Deliverable: Spoken answers to 2 reported Problem-solving / Case Studies question(s), under time.

Day 7 — Answer out loud: Behavioral / Leadership

• Answer aloud, timed: Describe a situation where you had to work with a difficult team member. How did you handle it?
• Answer aloud, timed: Can you give an example of a time when you had to adapt quickly to a change in project requirements?

Deliverable: Spoken answers to 2 reported Behavioral / Leadership question(s), under time.

Behavioural preparation

Behavioural rounds judge the decision you made and what it cost.

Describe a time you faced a technical challenge and how you resolved it.

Medium · Problem-solving / Case Studies

Approach

1. Pick a story where you made the decision, not one where you watched it.
2. State the situation in two sentences and spend the rest on the reasoning.
3. Give the blast radius: what could have broken, and what you measured.
4. Name the disagreement and how you resolved it with evidence.

Follow-up

• What would you do differently if you ran that again?
• How did you know your change caused the improvement?

Describe a situation where you had to work with a difficult team member. How did you handle it?

Medium · Behavioral / Leadership

Approach

1. Pick a story where you made the decision, not one where you watched it.
2. State the situation in two sentences and spend the rest on the reasoning.
3. Give the blast radius: what could have broken, and what you measured.
4. Name the disagreement and how you resolved it with evidence.

Follow-up

• What would you do differently if you ran that again?
• How did you know your change caused the improvement?

Can you give an example of a time when you had to adapt quickly to a change in project requirements?

Medium · Behavioral / Leadership

Approach

1. Pick a story where you made the decision, not one where you watched it.
2. State the situation in two sentences and spend the rest on the reasoning.
3. Give the blast radius: what could have broken, and what you measured.
4. Name the disagreement and how you resolved it with evidence.

Follow-up

• What would you do differently if you ran that again?
• How did you know your change caused the improvement?

What motivates you to perform well in your job?

Medium · Behavioral / Leadership

Approach

1. Pick a story where you made the decision, not one where you watched it.
2. State the situation in two sentences and spend the rest on the reasoning.
3. Give the blast radius: what could have broken, and what you measured.
4. Name the disagreement and how you resolved it with evidence.

Follow-up

• What would you do differently if you ran that again?
• How did you know your change caused the improvement?