**PySpark:** Expert\-level, hands\-on experience in developing, tuning, and optimizing large\-scale data processing applications using PySpark (Python for Apache Spark).
**SQL:** Mastery of Advanced SQL (including window functions, complex joins, stored procedures, and query performance tuning) across various database systems (e.g., Snowflake, Redshift, PostgreSQL).
**Programming:** Strong proficiency in Python for scripting, automation, and general data manipulation libraries (e.g., Pandas).
**Big Data Architecture:** Deep understanding of Big Data concepts, distributed systems architecture, data lakes, and modern data warehousing principles.
**ETL/ELT:** Proven experience in designing and implementing enterprise\-grade ETL/ELT pipelines.