Louis Tochon

SQL Server: why can’t I read the full table in parallel???

Why SQL Server keeps a full SELECT * serial: I/O cost is never divided across threads. Forcing parallelism burned 3x the CPU.

SQL Server: Stop ordering index columns by selectivity

Column order does not affect equality seeks in SQL Server. Measured on 5M rows, then proven inside the B-tree pages.

Why UUIDv7 does not reduce fragmentation in SQL Server

UUIDv7 places its timestamp first, but SQL Server compares uniqueidentifier values starting from the last bytes. Measured on 25,000 inserts: no gain over NEWID().

Fixing ORA-00904 on Oracle hidden columns during SSMA data migration

SSMA fails with ORA-00904 on Oracle SET UNUSED columns. Fix it with a custom select aliasing NULL, no source DDL required.

SQL Server vs MongoDB: When the cloud is your adversary (Always Encrypted vs Queryable Encryption)

When the cloud admin is the threat: how SQL Server and MongoDB let you query encrypted data, and what each approach costs.

Split, Sort, Collapse: how SQL Server survives an overlapping unique update

How SQL Server shifts a whole unique column by +1 without ever creating a duplicate using Split/Sort/Collapse.

When an idle transaction starves the worker pool (THREADPOOL)

How a forgotten transaction exhausted SQL Server's worker pool, triggered THREADPOOL waits, and only DAC could fix it.

Measuring the real performance cost of SQL Server XE buffers

Are Extended Events always lightweight? See how a bad config converts event loss into query latency through DMVs.

How Row Goal shapes your SQL Server query strategy by hunting for pierogis

Mastering SQL Server Row Goals and how TOP, EXISTS, and FAST N influence execution plans and how to avoid performance traps in your queries(…)

SQL Server 2025 In-Memory: New Cleanup Features & SQLBits 2026 Insights

SQL Server 2025 finally allows dropping In-Memory filegroups, a breakthrough analyzed here alongside expert performance insights from SQLBits 2026.