SQL from the bit up

Lessons

1. 01Rows, pages and filesA table is bytes in a file, read one page at a time. Learn the layout before you learn the language.○ not started
2. 02SELECT is a scanWithout an index, every SELECT is a loop over every row. See the loop, then learn the three ways engines make it shorter.○ not started
3. 03GROUP BY is a hash mapGROUP BY is one pass over the rows and a dictionary of running totals. Build it in Python, then read the SQL as the same thing.○ not started
4. 04Joins are loops and hash tablesA join is two loops, or one hash table and one loop. Know which, and you know why a join is fast, slow or silently wrong.○ not started
5. 05Window functions without the magicA window function is a sort, a split into partitions, and a walk down each one. Learn the walk and running totals, ranks and dedup stop being tricks.○ not started
6. 06Indexes are sorted copiesPlanned
7. 07NULL is not a valuePlanned
8. 08CTEs, subqueries and what the planner does with themPlanned
9. 09Reading a query planPlanned
10. 10Slowly changing dimensions with plain SQLPlanned