Blog · 5 files
| Name | Tags | Date | Read |
|---|---|---|---|
| October 2026 · 1 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 | |
| September 2026 · 2 posts | |||
| spark-repartition-vs-coalesce-aqe.md Partitioning in Spark: repartition(), coalesce() and Adaptive Query Execution How partition count shapes Spark performance, what repartition() and coalesce() really do, why coalesce(1) can push a whole job onto one task, and how Adaptive Query Execution (on by default since Spark 3.2) handles most partition tuning at runtime. Big Data | #spark #pyspark #performance | 6 min | |
| why-nolock-is-still-wrong.md Beyond NOLOCK: row versioning, RCSI and SQL Server 2025 optimized locking How NOLOCK really behaves (dirty reads, skipped and duplicated rows, error 601), how RCSI and SNAPSHOT isolation replace it, and what SQL Server 2025 optimized locking adds on top, including its limits. Databases | #sql-server #concurrency #performance | 7 min | |
| August 2026 · 2 posts | |||
| sqlite-insert-performance-ios.md Fast and safe bulk inserts in SQLite: transactions, WAL and iOS Why SQLite bulk inserts are slow by default, the three techniques that fix it, what synchronous=OFF and journal_mode=MEMORY really risk, why WAL with synchronous=NORMAL is a safer default, and how it all applies to Core Data, SwiftData and .NET. iOS Databases | #sqlite #ios #dotnet #performance | 8 min | |
| ef-core-bulk-insert-update-delete.md Bulk inserts, updates and deletes in EF Core: from SaveChanges batching to SqlBulkCopy How EF Core's batched SaveChanges differs from the EF6-era approach, how ExecuteUpdate/ExecuteDelete work and where they bite, EF Core 10's conditional setters, SqlQuery for unmapped types, and when to switch to SqlBulkCopy or PostgreSQL COPY. .NET | #dotnet #efcore #performance | 7 min | |