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# (Senior) Software Engineer - Data Core

- **Company:** Celonis
- **Location:** München, Germany
- **Experience:** Expert
- **Contract:** Permanent contract
- **Skills:** Java (Programming Language), Abstraction Layers, Adobe InDesign, Application Programming Interfaces (APIs), C++ (Programming Language), Code Review, Databases, Extract Transform Load (ETL), Software Debugging, Distributed Data Store, Python (Programming Language), PostgreSQL, Online Analytical Processing, Query Optimization, Queueing Systems, Standard Sql, SQL Databases, Snowflake, Apache Spark, Spring-boot, Backend, Integration Tests, Kubernetes, Free and Open-Source Software, Vertica, Grpc, Data Pipelines, Databricks
- **Published:** November 4, 2026
- **Apply:** https://startup.jobs/senior-software-engineer-data-core-celonis-10659039

## About the Role

* Solid Java, or strong Python with the willingness to work in Java daily.
 * Good SQL skills: joins, aggregations, window functions, and an understanding of how queries execute.
 * Familiarity with at least one analytical or distributed data system (for example Spark, Snowflake, Databricks, Trino, ClickHouse, or StarRocks).
 * Good testing and debugging habits.
 * Clear written and spoken communication, and a habit of asking questions early.

Strong Plus

 * Exposure to how SQL parsers, ASTs, or query planners work.
 * Contributions to open source projects, especially sqlglot or StarRocks.
 * Experience with gRPC, message queues, or Kubernetes.
 * Some C++ experience.
 * Interest in query optimization and database internals.

## Description

Data Core is the storage abstraction layer behind Celonis' data pipelines. It sits between ETL workloads and the backends that run them, such as Databricks, Snowflake, StarRocks, Spark, and PostgreSQL. You will work mainly on three codebases:

 * Data Core, a Java / Spring Boot service with gRPC and message-queue APIs.
 * sqlglot, where we translate and optimize SQL across dialects.
 * StarRocks, the OLAP engine we use as a backend.

What You Will Do

 * Implement features and fix bugs in Data Core backend integrations.
 * Add and fix sqlglot dialect support: parsing, SQL generation, and transpilation correctness.
 * Investigate StarRocks behavior and compatibility issues, and contribute fixes or workarounds.
 * Debug slow or incorrect queries by following them from SQL text to query plan to results.
 * Write unit and integration tests, especially for SQL translation edge cases.
 * Take part in design discussions, write short design docs for your own work, and give and receive code reviews.
 * As a Senior: lead small to medium projects end to end and help onboard newer teammates.