I have extensive experience with Power BI, having developed numerous reports and dashboards for various clients. I am proficient in data modeling, DAX queries, and creating interactive visualizations. Additionally, I have worked with SSRS to generate complex reports from SQL Server databases, ensuring data accuracy and report efficiency.

I follow a rigorous validation process that includes cross-referencing data sources, performing multiple test runs, and involving stakeholders for feedback. I also automate data validation scripts to catch discrepancies early. By maintaining detailed documentation and version control, I ensure that any changes are traceable and reliable.

When dealing with large datasets, I focus on optimizing data retrieval and processing. This involves using efficient SQL queries, indexing, and partitioning techniques. I also leverage in-memory processing capabilities of tools like Power BI and SSRS to handle large volumes of data without compromising performance.

I use version control systems like Git to track changes and maintain a history of report versions. For documentation, I create comprehensive guides that include data sources, report logic, and user instructions. This ensures that any team member can understand and maintain the reports, even if I am not available.

One challenging project involved integrating data from multiple, disparate systems into a single, cohesive report. I overcame this by creating a data warehouse to centralize the data and using ETL processes to ensure data consistency. I also implemented dynamic filtering and drill-down capabilities to enhance user interactivity and report usability.