Relational algebra, set operations and SQL. I learnt the power of parallel queries on massive datasets when directly manipulated with relational algebra, set op

Relational algebra, set operations and SQL. I learnt the power of parallel queries on massive datasets when directly manipulated with relational algebra, set ops and SQL. For eg: Create Table XX as Select a, b, c from YY, ZZ where ... Lambdas, async and Linq. Somewhat related to the previous point, but combining these three helps with writing expressive and powerful declarative and functional code.