Senior Software Engineer, Query

MongoDB
Full-time•Full-stack•Dublin, Ireland · Remote within Ireland · Hybrid
Apply Now

TechJobs.ie Job Insights

At a glance

Employment type
Full-time
Workplace
Hybrid
Category
Full-stack

Technologies & skills

Primary technologies

Cloud & infrastructure

Other technical skills

What you'll be doing

Join MongoDB's Query Testing Tools Team in Dublin to design, develop, and maintain automated testing frameworks and performance tools for the distributed query engine. Collaborate with peers to ensure testability and code robustness, focusing on correctness and performance for customer-critical workloads.

  • Design, develop, and maintain automated testing frameworks, performance automated tests, and internal tooling for the MongoDB query engine
  • Collaborate closely with peers to understand new features and functionalities, ensuring testability, test frameworks, tooling, and coverage for automating tests
  • Provide feedback in code reviews, focusing on the robustness and reliability of code changes

Key requirements

Must-have

  • 5+ years of experience in software development and/or performance engineering
  • Fluency in Python, JavaScript or TypeScript
  • Ability to solve complex problems in a distributed environment
  • Strong written and spoken English communication skills
  • Ability to decompose and solve complex problems and rapidly iterate

Nice-to-have

  • Hands-on experience with relational or NoSQL databases
  • Advanced degrees or experience in database query engines
  • Experience developing automation test frameworks
  • Experience in query processing engine testing
  • Experience developing performance test plans and monitoring frameworks
  • Background in database query engines or compilers

Experience: 5+ years

Role signals

Technical focus
testing frameworks, performance tools, distributed systems
Hands-on vs management
Hands-on

Full job description

The MongoDB Query Testing Tools Team is hiring Software Engineers who want to join us in building a state-of-the-art distributed query system. Our Team builds tooling that allows us to ship Query Engine features with high confidence in both correctness and performance, making it a great fit if you like seeing your work protect real customers at scale. The team develops advanced testing frameworks (end-to-end testing, fuzzing, property-based testing) as well as performance measurement tools, including high-volume workload generation tools.

The team is part of the Query organization which is responsible for the MongoDB Query Language and the lifecycle of each query, from parsing to optimization to plan selection; our engineers work on maintaining and improving our optimization and execution frameworks and building new query language features to help power our customers' critical workloads. Throughout all our work, our highest priority is always ensuring that customer queries are answered correctly. The successful applicant will be responsible for helping us to maintain the highest standards of quality through rigorous development, testing and automation strategies.

We are looking to speak to candidates who are based in Dublin for our hybrid working model.

Candidate Profile

  • 5+ years of experience in software development and/or performance engineering

  • Fluency in Python, Javascript or Typescript

  • Enjoys chasing down difficult problems in a distributed environment

  • Able to make complex concepts easy to grasp in written and spoken English

  • Able to decompose and solve complex problems and can rapidly iterate by validating new hypotheses and rethinking current assumptions

  • Demonstrating hands-on experience working with relational or NoSQL databases is a plus

  • B.Sc. in Computer Science or related field, or equivalent practical experience. Advanced degrees of experience in database query engines is a plus

  • Experience in developing automation test frameworks is a plus

  • Experience in query processing engine testing is a strong plus

  • Experience in developing performance test plans and monitoring frameworks is a strong plus

  • Background in database query engines or compilers is a strong plus

Position Expectations

  • Design, develop, and maintain automated testing frameworks, Performance automated tests and internal tooling for the MongoDB query engine

  • Collaborate closely with peers to understand new features and functionalities, ensuring testability, test frameworks, tooling and coverage for automating tests of both happy-path and edge-case scenarios

  • Provide feedback in code reviews, focusing on the robustness and reliability of code changes

Success Measures

  • Within three months, you have gained an understanding of MongoDB's MQL syntax and its semantics, as well as the behavior of our unique query engine. You have contributed to several code bases on Mongodb engine internal tooling

  • By six months, you have established yourself as a key owner of automated test frameworks, and demonstrated improvements in test efficiency and coverage

  • After twelve months, you are instrumental in ensuring quality of major new features, setting an example for new team members in best practices for correctness and performance test automation and internal tooling

About MongoDB

MongoDB is built for change, empowering our customers and our people to innovate at the speed of the market. We have redefined the data platform for the AI era, enabling builders to create, transform, and disrupt industries with software. MongoDB’s unified data platform, the most widely available, globally distributed data platform on the market, helps organizations modernize legacy workloads, embrace innovation, and unleash AI. Our cloud-native platform, MongoDB Atlas, is the only globally distributed, multi-cloud data platform and is available across AWS, Google Cloud, and Microsoft Azure.

With offices worldwide and over 67,000 customers, including AI-native startups and approximately 75% of the Fortune 100, relying on MongoDB for their most important applications, we’re powering the next era of software.

Our compass at MongoDB is our Leadership Commitment, guiding how and why we make decisions, show up for each other, and win. It’s what makes us MongoDB.

To drive the personal growth and business impact of our employees, we’re committed to developing a supportive and enriching culture for everyone. From employee affinity groups, to fertility assistance and a generous parental leave policy, we value our employees’ wellbeing and want to support them along every step of their professional and personal journeys. Learn more about what it’s like to work at MongoDB, and help us make an impact on the world!

MongoDB is committed to providing any necessary accommodations for individuals with disabilities within our application and interview process. To request an accommodation due to a disability, please inform your recruiter.

MongoDB is an equal opportunities employer.

Req ID: 3273588903

Interview prep pack

Grounded in this listing. Use it to prepare examples before you apply.

Your interview focus

Based on this listing, the Senior Software Engineer, Query role at MongoDB focuses on building and maintaining advanced automated testing and performance measurement tools for the MongoDB query engine, with an emphasis on correctness, reliability, and distributed systems problem-solving.

  • Distributed systems problem-solving·High
  • Automated testing and performance tooling·High
  • Collaboration and communication·Medium

Only have 30 minutes?

Follow a focused preparation plan based on this job.

Start 30-minute prep

Your 30-minute plan

  1. Review MongoDB Query Engine and MQL

    0–8 min

    Spend time understanding MongoDB's query language and how its query engine works, focusing on parsing, optimization, and execution.

  2. Prepare Examples of Automated Testing and Performance Tools

    8–15 min

    Select 2-3 strong examples from your experience where you built or improved automated test frameworks or performance measurement tools, especially in distributed systems.

  3. Reflect on Distributed Systems Problem-Solving

    15–21 min

    Think through specific instances where you diagnosed and resolved complex issues in distributed environments, noting your approach and outcomes.

  4. Review Collaboration and Code Review Practices

    21–26 min

    Recall situations where you provided or received feedback in code reviews, focusing on how you ensured code robustness and reliability.

  5. Draft Role-Specific Questions

    26–30 min

    Prepare thoughtful questions to ask the interviewers about the team, processes, and growth opportunities.

Likely questions

, 6 items

Priority reflects how strongly this topic is emphasised in the job listing, not whether it will be asked.

Talking points

, 5 items
  • Designing and Maintaining Automated Test Frameworks

    You will need to demonstrate experience building robust, scalable test frameworks that ensure correctness and performance in complex systems.

  • Performance Testing and Monitoring

    The role emphasizes developing tools for high-volume workload generation and performance measurement; be ready to discuss how you have approached similar challenges.

  • Solving Complex Problems in Distributed Environments

    You should prepare examples of diagnosing and resolving difficult issues in distributed systems, as this is central to the team's work.

  • Collaboration and Code Review

    The position requires close collaboration with peers and providing feedback in code reviews, so be ready to discuss your approach to teamwork and maintaining code quality.

  • Working with Query Engines or Databases

    Hands-on experience with query engines or databases is a strong plus; prepare to discuss relevant projects or contributions.

What to research

, 4 items
  • MongoDB Query Engine and MQL Syntax

    Review the basics of MongoDB's query language (MQL) and understand how the query engine processes and optimizes queries.

  • Automated Testing Frameworks and Performance Tools

    Prepare examples of frameworks or tools you have built or used for automated testing and performance measurement, especially in distributed systems.

  • Distributed Systems Debugging

    Be ready to discuss your approach to diagnosing and resolving issues in distributed environments, including tools and methodologies.

  • Collaboration and Code Review Practices

    Reflect on your experience collaborating with peers, especially in code reviews and ensuring code quality.

Questions to ask

, 6 items
  1. What are the biggest challenges currently faced by the Query Testing Tools Team?

    Why ask this? To understand the team's pain points and how your skills can address them.

  2. How does the team measure the effectiveness of its automated testing and performance tools?

    Why ask this? To learn about success metrics and expectations for the role.

  3. What is the process for introducing new features or changes to the query engine, and how is test coverage ensured?

    Why ask this? To clarify the development and testing workflow.

  4. How does the team collaborate with other parts of the Query organization or with product teams?

    Why ask this? To gauge cross-team interaction and communication expectations.

  5. What opportunities are there for contributing to the design or architecture of new testing frameworks?

    Why ask this? To assess the potential for technical ownership and innovation.

  6. How does the team stay up to date with advances in testing methodologies or distributed systems?

    Why ask this? To understand the team's commitment to learning and improvement.

Register now to upload your CV

Create a free account, save a PDF or Word CV, and quick apply on roles that take applications here.

Apply NowApply before: 20 Nov 2026