Stephan Martin
Sabbatical, further training
Experience
Jan 2024 - Present
1 year 7 monthsSabbatical, further training
Freelancer
- Topics: Snowflake, Google Looker
- LLMs: local models (Llama, Mistral, Gemma, Phi, Qwen, DeepSeek, Bitnet, Flux, Whisper), OpenAI API, frontends (ollama, openwebui, loacalai), inference (llama.cpp, vLLM, transformer), quantization, benchmarking, prompting
- LLM agents: Tool/Function Calling, LangChain, LangGraph, MCP
- Other: attention, reasoning, chain of thought, RAG, GraphRAG, MLflow
- Cloud hosted: ChatGPT, Claude, Gemini
Jan 2022 - Dec 2023
2 yearsBerlin, Germany
Data Engineering Architect, Data Analyst, Data Engineer
Init AG
- Technical environment: Confluence, Jira, MS Teams, Cisco Webex, GitLab, git, WSL2, DBeaver, Jupyter, vim, bash, PostgreSQL, psql, Python, MS Excel, VS Code, Java/Freemarker, amCharts 5, TypeScript
- Requirements analysis, design, data modeling, development, testing, documentation, operation and maintenance, change requests, optimization, reporting
- Approach: agile
Jul 2021 - Dec 2021
6 monthsBerlin, Germany
Data Engineer
D4L data4life gGmbH
- Technical environment: Confluence, Jira, Slack, Google Workspace, GitHub, Docker/Kubernetes, PostgreSQL, Airflow, Python, Metabase
- Integration of BI event data, mapping of JSON data, building the data model
- Replaced a backend service database as data source with BI events
- Source systems: microservices in Golang, EventStore Elasticsearch; data delivery as JSON into PostgreSQL
- Mapping to relational modeling with SQL views, generating SQL from YAML
- ETL using Airflow DAGs, test environment in Docker, reporting with Metabase
- Design, implementation, testing, coordination with developers, data analysis, documentation, database optimization
Apr 2020 - Jun 2021
1 year 3 monthsCOVID-19 (risk group)
Self-Employed
Due to being in a household risk group and caring for a child, no projects were taken on
Apr 2018 - Mar 2020
2 yearsFrankfurt, Germany
Data Engineer
DB Analytics (Deutsche Bahn)
- Technical environment: AWS EC2, S3, Aurora, PostgreSQL, PostGIS, MS SQL, 3NF modeling, Git, GitLab, Docker, Ubuntu Server, OpenSUSE, MS Windows, Python (yaml, psycopg2, SQLAlchemy, graphviz), Bash, SQL, PL/pgSQL, R, REST, JSON, CSV, Confluence, Jira, Slack, MS Teams
- Design, implementation and maintenance of a data mart and ETL for analyzing energy savings of DB Cargo
- Comparison of data quality of IoT devices from various vendors to assess DB Schenker's line transports
- Analysis of IoT device geodata: stop detection with R and PostGIS, geofencing
- Design and implementation of a DWH and ETL for evaluating DB Schenker's scheduled services
- Using YAML for metadata, Bash/Python for data ingestion, PL/pgSQL for transformation, logging, error reporting
Nov 2015 - Oct 2017
2 yearsLeverkusen, Germany
Technical Project Manager, IT Engineer
Bayer Business Services GmbH
- Technical environment: Windows Server/Cluster, MS SQL Server, SSMS, SSDT, SSIS, SSAS, SSRS, HPSM, Lotus Notes, MS Office, Jira, Git, VS Code, PowerShell, RDP
- Developed a tool to support MS SQL licensing using PowerShell, MS SQL, Excel
- Implemented PAM and IAM roles with least privileges: concept, PoC, managed service control
- IAM and PAM analysis, reporting on MSSQL logins, evaluation according to corporate guidelines
- Database transition: analysis, target state, guidelines, checklists, scripts, transition management
- SQL lifecycle management: analysis, target state, reporting, scripts, updates, handover to managed service
Feb 2015 - Jul 2015
6 monthsViernheim, Germany
Technical Consultant
Degoya Medienkommunikation oHG
- Technical environment: MODX, Ext JS, MySQL
- Designed and implemented a reservation and voucher system for the hospitality industry
Nov 2013 - Apr 2014
6 monthsNeuenstein, Germany
Technical Consultant
GLS
- Technical environment: DB2, Siebel, Informix, Stored Procedures, Shell
- Designed and implemented interfaces for data migration and system integration
Jan 2010 - Apr 2012
2 years 4 monthsKarlsruhe, Germany
Architect Business Intelligence – Customer Care
1&1 Internet AG
- Technical environment: Sybase ASE, PostgreSQL, Perl, Bash, Excel, Talend, Pentaho Kettle, star/snowflake schema, 3NF
- Business intelligence strategy, developing new KPIs, connecting new data sources
- Requirements management, design of data models and ETL processes, data analysis for project management
- Projects: connecting SABIO to DWH, infrastructure for near real-time reporting, evaluating Talend/Pentaho
Apr 2008 - Dec 2009
1 year 9 monthsKarlsruhe, Germany
Head of Business Intelligence – Customer Care
1&1 Internet AG
- Technical environment: Sybase ASE, Sybase IQ, star/snowflake schema, SSAS OLAP
- Built and led BI Customer Care (6 staff), strategic direction, system integration
- Requirements management, infrastructure expansion, process implementation, staff development
- Projects: evaluating MS SQL Server, implementing slowly changing dimensions, consolidating dimensions, preparing MicroStrategy
Apr 2007 - Mar 2008
1 yearKarlsruhe, Germany
Developer Business Intelligence
1&1 Internet AG
- Technical environment: Sybase IQ, OLAP, star/snowflake schema, 3NF, Perl, Excel
- Defined, implemented and quality-checked control metrics for support centers
- Data analysis for project controlling, dashboard development for Access products
Jul 2002 - Mar 2007
4 years 9 monthsWiesbaden, Germany
Head of Data Management
Schlund+Partner AG
- Technical environment: Sybase ASE, MySQL, Sqsh, Perl, Debian
- Built and led data management (5 staff), resource planning, subproject planning
- Process monitoring, data modeling, staff development
- Projects: internationalization of hosting products, migration to 1&1, migration of Web.de products
Oct 2000 - Jun 2002
1 year 9 monthsWiesbaden, Germany
Developer Data Management
Schlund+Partner AG
- Technical environment: Sybase ASE, OLTP, Sqsh, Bash, Perl, XML, XSLT, SUSE Linux
- Ensured consistency of technical customer attributes, maintained tariff and contract data
- Incident and problem management, process and data modeling, framework development
Dec 1998 - Oct 2000
1 year 11 monthsWiesbaden, Germany
Support
Schlund+Partner AG
- Phone support for hosting products outside business hours
Oct 1997 - Nov 1998
1 year 2 monthsWiesbaden, Germany
Developer
Schlund+Partner AG
- Technical environment: Perl, PHP, SQL, Solid DBMS, OLTP, Apache, IRIX, Debian, SUSE Linux
- Developed and maintained the “Private Homepages” product, backed up all Unix servers and workstations
Summary
Over 30 years of IT experience solution-oriented, sustainable, analytical, creative
Languages
German
NativeEnglish
AdvancedEducation
Flinders University
Computer Science · Adelaide, Australia
Universität Kaiserslautern, Fernuni Hagen
Diploma · Computer Science · Hagen, Germany
Certifications & licenses
Google Looker
credly.com
Snowflake - Hands-On Essentials
Snowflake
CDVP2 Certified Data Vault 2.0 Practitioner
ScaleFree
Dbt Fundamentals
learn.microsoft.com
Microsoft AI Fundamentals (AI-900)
learn.microsoft.com
Microsoft Azure Fundamentals (AZ-900)
learn.microsoft.com
Microsoft Data Fundamentals (DP-900)
learn.microsoft.com
Microsoft Power Platform Fundamentals (PL-900)
learn.microsoft.com
MicroStrategy Architect
MicroStrategy
MicroStrategy Reporting
MicroStrategy
Fundamentals of Microsoft Office Project Server 2007
Campana & Schott
Certified ScrumMaster
Certified ScrumMaster
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