Videos

https://www.youtube.com/watch?v=xrMbzHdPLKM

https://www.youtube.com/watch?v=RpoC3UcG5YA

https://www.youtube.com/watch?v=xrMbzHdPLKM

PostgreSQL 9.6. How config performs in high-write workloads.

https://www.youtube.com/watch?v=n5-xEEQFqPY

PostgreSQL In-Depth Training

B-tree, index, PostgreSQL 13.

Fundamentals are high-level overview.
Recommend the Performance Part 1 & Part 2.