SQL
Getting the data out and computing where it is cheapest to compute.
4 articles, newest first.
- Incremental tables that do not drift Full rebuilds stop being affordable, incremental builds start being wrong. How to pick the incremental key, handle late data, and catch drift before a stakeholder does.
- Cohort retention in SQL, without the spreadsheet How to build a retention table that survives contact with real data: cohort definition, a period spine, and the bug that makes retention look like it is improving.
- SQL or pandas? Push the heavy lifting to the database A practical rule for splitting work between the warehouse and your laptop: aggregate where the data lives, iterate where your tools live.
- The four SQL window functions that do 90% of the work ROW_NUMBER, LAG, SUM OVER, and moving averages — with the patterns for deduplication, sessionisation, and running totals you will reuse for years, plus FILTER, QUALIFY, ROWS versus RANGE, and what a window actually costs.