Blog · 2 files
| Name | Tags | Date | Read |
|---|---|---|---|
| October 2026 · 2 posts | |||
| first-row-per-group-sql.md Top-N per group in SQL: matching the query to your data A guide to selecting the first or top-N row per group in SQL Server, PostgreSQL, EF Core and Spark: how each pattern executes, why data distribution decides which one wins, which indexes they need, and how to verify the choice in the plan. Databases | #sql #sql-server #postgresql #performance | 8 min | |
| upsert-sql-server-postgresql-sqlite-guide.md Concurrency-safe upserts in SQL Server, PostgreSQL and SQLite How upserts break under concurrency and how to write them safely: UPDLOCK and SERIALIZABLE or MERGE in SQL Server, ON CONFLICT, MERGE and RETURNING in PostgreSQL, native UPSERT in SQLite, and why INSERT OR REPLACE is not one. Databases | #sql #sql-server #postgresql #sqlite | 7 min | |