Daniel Henneberger, Developer in Eugene, OR, United States
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Daniel Henneberger

Verified Expert  in Engineering

Back-end Developer

Eugene, OR, United States
Toptal Member Since
November 17, 2020

For the past few years, Daniel has been working on enabling developers to build software faster and easier. He's developed novel query optimizers for NoSQL databases, created machine learning algorithms for big data in adtech, and built novel high-performance API gateways for databases. As a full-stack developer, Daniel has worked with many programming languages including, Java and GraphQL. He's also created foundational software for companies and managed small engineering teams.


Apache Airflow, Microservices, Open Source, Dropwizard, OpenLineage, Python...
Cassandra, NoSQL, Java
Clustering, Natural Language Processing (NLP), GPT...




Preferred Environment


The most amazing...

...project I've worked on was developing a relational query engine on top of Cassandra.

Work Experience

Software Engineer

2020 - PRESENT
  • Participated in the open-source development of the Marquez and Open Lineage project. Extended Marquez to provide additional operators for the Apache Airflow data pipeline tool.
  • Assisted in developing the OpenLineage specification for widespread adoption in data pipeline tools. Assisted with dataset versioning, run versioning, and job versioning concepts for data pipeline management aspects.
  • Applied data modeling expertise to provide scalable solutions for the database layer. Developed PostgreSQL table partition implementations for time series data.
Technologies: Apache Airflow, Microservices, Open Source, Dropwizard, OpenLineage, Python, Java

Senior Software Engineer

2018 - 2020
  • Worked as a software engineer under DataStax's Chief Technologist to develop a new kind of data platform on top of the Cassandra database stack that would enable enterprises to quickly operationalize their data.
  • Developed a query optimizer on NoSQL databases to find minimal query plans given the schema, workload, and constraints; enabled the optimizer to receive inputs from the user about advanced data features to allow decisions beyond conventional optimizers.
  • Functioned as the sole back-end engineer for the SaaS platform until the team grew.
  • Developed several pieces of core functionality individually and with a small team.
  • Planned engineering work and delegated responsibilities.
Technologies: Cassandra, NoSQL, Java

Principal Software Engineer

2015 - 2018
  • Worked as a full-stack software engineer for a big data analytics team. Developed new strategies for resolving data analytic queries faster. Created data pipelines for new data to enable Customer 360 applications.
  • Built applications for natural language processing, high dimensional clustering algorithms, search, and analytics. Assisted in the development of a novel distributed database to apply machine learning at scale.
  • Developed data visualization, microservice interaction tracing, and in-memory analytics to create actionable insights for developers and BI teams.
Technologies: Clustering, Natural Language Processing (NLP), GPT, Generative Pre-trained Transformers (GPT), Machine Learning, Microservices, Java

Software Engineer

2014 - 2015
Mesoscale Discovery
  • Developed cloud-based laboratory management software for the biodefense, clinical, and life-science markets.
  • Implemented data-driven procedures for automated reagent dispensing systems and codified validated protocols for micro-plate test kits.
  • Developed highly tested and documented software consistent with FDA regulated software systems.
Technologies: Amazon Web Services (AWS), Biotechnology, Java

Graduate Assistant

2011 - 2013
Frostbug State University
  • Assisted in teaching and held labs for the computer science department. Lectured, developed course material, and mentored students.
  • Led students in computer science-related extracurricular activities, including computer security competitions, recruitment efforts, and other department software projects.
  • Administered the computer science GRE subject test.
Technologies: Java, Education

Applications Engineer

2010 - 2011
  • Developed flagship java business process management software for the Department of Justice (DOJ) and the Internal Revenue Service (IRS) in a proprietary Java J2EE framework.
  • Worked on-site for the IRS to collect business requirements and independently developed several small Java projects.
  • Held public trust and secret security clearances for DOJ and IRS.
Technologies: Apache Velocity, Spring, Java

Web Developer

2008 - 2010
Concept C Marketing & Design
  • Constructed a WordPress website for a hair salon to highlight their products and provide location-aware pricing; building the site WordPress allowed the owner to implement changes.
  • Developed a website for a mall to provide a directory of stores and highlight winter promotions.
  • Worked closely with designers to assure that designs could be quickly created.
Technologies: WordPress, PHP, Java, Foundation CSS

GraphQL NoSQL Query Optimizer

A NoSQL query optimizer that works with an annotated GraphQL schema to create an optimized database schema. It features time-series compatibility and allows the ordering by date, immutable fields, including fields that span relationships.


Java, GraphQL, Rust, Python, PHP




NoSQL, Cassandra


Dropwizard, Spring, Apache Velocity, Foundation CSS


Apache Airflow


WordPress, Amazon Web Services (AWS)


Data Structures, Machine Learning, Computer Vision, Natural Language Processing (NLP), Clustering, OpenLineage, Open Source, Biotechnology, Education, GPT, Generative Pre-trained Transformers (GPT)

2011 - 2013

Master's Degree in Computer Science

Frostburg State University - Frostburg, MD, United States