Jeff Brennan

senior data engineer

I’m a data engineer with a background in public health, motivated by better care for underserved communities. I build reliable data platforms, improve performance, and make working with data easier through thoughtful tooling and mentorship.

At Astrana Health, my work spans a shared Databricks platform, patient matching at a scale of 6.5 million patients, and APIs that bring claims and quality data to care teams. I also contribute to open source and build developer tools, including sparkparse, a parser that helps diagnose Spark performance problems.

Resume

Skills

  • Healthcare data: PHI under HIPAA, Epic Clarity, claims, HL7, CCDA, CMS CCLF
  • Coding and measures: ICD, CPT, NDC, quality measures
  • Languages: Python, SQL, R
  • Platform: Databricks, Spark, PySpark, Delta Lake, Unity Catalog, Docker, Azure
  • Pipelines and delivery: CI/CD, Azure Data Factory, Azure DevOps, Databricks Jobs, Dagster, pytest, Pydantic
  • Serving and apps: PostgreSQL, GraphQL, Databricks Apps, Svelte, Power BI, Tableau, Plotly Dash
  • Certifications: Databricks Data Engineer Professional, Epic Clinical Data Model

Experience

Senior Data Engineer at Astrana Health
Jul 2025 - Present
  • Built and own the EMPI: Splink matching for 6.5M patients across 23 source systems, with a 91M-record auditable match history
  • Extended the EMPI with a Svelte Databricks app that reviews flagged clusters as a whole, replacing notebook review that compared record pairs one at a time
  • Technical lead, clinician-facing serving layer for 64 physician groups: built the incremental sync and most of the GraphQL API and PostgreSQL models
  • Built release CI/CD for apps, views, and dashboards: about 16 releases a week, a 12-minute median merge to live, 18 people releasing without prod admin
  • Built the production observability app over about 150 jobs, nearly 20 apps, and 60+ materialized views; added runaway-job termination and spend alerts
  • #1 of 66 PR authors across 4 platform repos; reviewer on 63% of others’ PRs and one of two production-merge approvers
Data Engineer at Medisolv
Jul 2023 - Jul 2025
  • Owned ingestion for hundreds of hospital clients, including Epic Clarity: 10B+ records weekly into a 150TB+ lake, with Event Hubs telemetry for stalled tasks
  • Migrated 1,500+ Azure Data Factory pipelines to source control: code review, rollback, one-button deploys, Pydantic/pytest validation
  • Automated client onboarding with Python and the Azure SDK: over a day of manual setup down to a five-minute deployment
  • Open sourced sparkparse, a Spark metrics parser; its findings cut tasks from hours to 10–20 minutes
Data Engineer (part-time contract) at UTHealth
May 2020 - Sep 2023
repo
  • Ran the daily Texas COVID-19 dashboard pipeline, with unit tests and Slack data-quality alerts
Data Analyst at NewYork-Presbyterian
Dec 2020 - Jul 2023
cost savings article
  • Built weekly ELT for CMS quality reporting: 100M+ records a week for 35,000 Medicare patients in a shared-savings program
  • Modeled score against sample size to set CMS reporting depth
  • Cut Tableau load times from 2–3 minutes to under 10 seconds with pre-aggregated tables and a star schema
Research Coordinator I at Baylor College of Medicine
June 2017 - Nov 2019
thesis
  • Authored thesis (100+ citations) on biomarkers of traumatic brain injury (TBI) and provided data support for other research efforts
  • Applied variable selection on hundreds of biomarker combinations to identify TBI predictors
  • Built analysis pipelines and created publication-ready data visualization in R

Education

2018 - 2020
Master of Science in Epidemiology
UTHealth Houston
GPA: 3.8
  • Minored in biostatistics, with a thesis on biomarkers of traumatic brain injury (TBI)
  • Certificate in Data Science
  • Coursework included biostatistics, applied machine learning, and study design
2014 - 2018
Bachelor of Science in Public Health
University of Texas at Austin
GPA: 3.7

Studied public health, with coursework spanning biostatistics, infectious disease microbiology, and global health.

Extracurricular Activities

  • President of SURGe - a student-led organization connecting STEM faculty with students needing research experience

Projects

sparkparse
Spark metrics parser that exposes exploding joins and memory pressure to guide performance improvements
Python Spark OSS devtools
Panoctagon
Combat sports database and dashboard
Python Dagster dbt Plotly Dash DuckDB FastAPI CLI
jpmdb
Small data cleaning project to create a personalized movie database for my friend
Python Dagster dbt Plotly Dash DuckDB
Quinn
PySpark helper library downloaded 600k+ times per month
Python PySpark OSS devtools
TexasPandemics
Collection of epidemiology data powering the UTHealth COVID-19 dashboard
R Python Selenium REST Tableau