Denys S.

Power BI and Apache Superset developer. 4.5+ years building analytics that teams actually open every morning. Top Rated Plus · 100% Job Success · 1,500+ hours · 18 projects delivered I work on production BI: dashboards used by up to 200 people, sitting on datasets in the tens of millions of rows. I take a project from "we have data somewhere and no idea what it's telling us" through to a working, documented, self-refreshing solution your team can run without me. ━━━━━━━━━━━━━━━━━━━━━━ POWER BI Microsoft PL-300 certified, and my day-to-day for 4.5+ years across enterprise and freelance projects. • End-to-end delivery: data model design, Power Query ETL, DAX measures, publishing and lifecycle in Power BI Service • Performance work: model redesign, DAX optimisation, incremental refresh, aggregation strategy • Governance: Row-Level Security, gateways, dataflows, field parameters • Automated refresh and monitoring, so reports keep working when nobody is watching them • Rescue work on inherited reports - slow, broken, undocumented, or built by someone who left ━━━━━━━━━━━━━━━━━━━━━━ APACHE SUPERSET Superset is where most of my recent work sits, and it's a skill very few BI freelancers actually have in production. • Dashboards and charts built to spec - including custom HTML/CSS visuals via Handlebars when the native chart library doesn't do what the stakeholder wants • SQL Lab, virtual datasets • Query and dashboard performance tuning on large tables • Roles, permissions and row-level access control • Migration from Power BI or Tableau to Superset - rebuilding data models, re-implementing business logic, cutting licence costs without losing functionality • Deployment and configuration (Docker, database connections, environment setup) when you don't have a data engineer to hand If you've adopted Superset and hit the wall where the out-of-the-box charts stop being enough - that's the exact problem I solve. ━━━━━━━━━━━━━━━━━━━━━━ SQL & DATA MODELLING • PostgreSQL, MS SQL Server (SSMS), Azure Data Studio • Star-schema design from raw operational sources • Views, stored procedures, CTEs, window functions • Query optimisation - most "slow dashboard" problems are actually slow query problems ━━━━━━━━━━━━━━━━━━━━━━ EXCEL & GOOGLE SHEETS Still a large part of what clients need, and I do it properly: • Calculation, forecasting and budgeting models • Power Query automation instead of manual copy-paste • Interactive templates with dynamic filters and charts ━━━━━━━━━━━━━━━━━━━━━━ HOW I WORK 1. Requirements first. I talk to the people who will actually use the dashboard, not just the person who hired me. Half of BI projects fail because nobody asked what decision the report is supposed to support. 2. Model, then visuals. A clean data model makes everything after it fast and cheap to change. Skipping this is why so many dashboards are unfixable six months later. 3. Documented handover. You get the logic written down - metric definitions, refresh schedule, known limitations. No lock-in, no dependency on me. 4. Support after delivery. Available for changes, extensions and troubleshooting once the project ships. ━━━━━━━━━━━━━━━━━━━━━━ RESULTS • Cut a Power BI dataset refresh from 20 minutes to seconds by redesigning the model around incremental refresh - the report went from "check it in the morning" to genuinely current • Migrated over 7 dashboard reporting suite from Power BI/Tableau to Apache Superset - models rebuilt, business logic re-implemented, per-seat licence cost removed, no loss of functionality • Diagnosed slow Superset dashboards by reading query execution plans and rewriting the SQL underneath them. The fix is almost always in the query, not the chart • Replaced a manual finance calculation that consumed hours of an analyst's week with a fully automated report - the manual process no longer exists • Delivered dashboards serving up to 200 users in Power BI and 50-60 in Superset, across roughly 40-80 production dashboards in each tool ━━━━━━━━━━━━━━━━━━━━━━ DOMAINS I KNOW SaaS and IT services · HR and recruiting · Finance and accounting · E-commerce and retail · Marketing analytics ━━━━━━━━━━━━━━━━━━━━━━ Certifications: Microsoft PL-300 Power BI Data Analyst · Google Data Analytics Professional Certificate · Google Analytics IQ · Alteryx Foundational Education: MEd, Information Technology (2025) Send me an invite with a short description of your data and what you're trying to see. I'll tell you straight away whether it's a two-day job or a two-month one, and whether Superset, Power BI or something simpler is the right answer. Keywords: Apache Superset, Power BI, DAX, Power Query, SQL, PostgreSQL, SQL Server, data modeling, star schema, ETL, data visualization, dashboard development, KPI dashboard, business intelligence, BI migration, report automation, RLS, Looker Studio, Excel, Google Sheets, financial reporting, executive dashboard, data analytics, performance optimization