sql

B+ trees are the workhorse of relational databases. Learn why their high fanout and shallow depth match disk perfectly, how point lookups and range scans work, the difference between clustered and secondary indexes, how covering indexes eliminate table lookups, and the hidden write cost of keeping indexes up to date.

Learn how to combine data from different tables in a relational database using the four fundamental SQL JOIN types: INNER, LEFT, RIGHT, and FULL OUTER. We'll explore what each join does, when to use it, and how they differ, using clear examples and diagrams.

Dive deep into the world of PostgreSQL indexes. Understand the core mechanics of B-tree, Hash, GIN, and GiST indexes, their optimal use cases, and how to choose the right indexing strategy to dramatically accelerate your database queries.

Learn the foundational concepts of Snowflake, the cloud-native data platform. Explore its unique architecture, key features like time travel and zero-copy cloning, and understand how its pricing model works.

Learn the fundamentals of dbt (data build tool), the industry standard for transforming data directly within your cloud data warehouse. This lesson covers core concepts like models, materializations, sources, and testing, empowering you to build reliable and modular data pipelines with just SQL.