INSERT, UPDATE, and DELETE operations look simple on the surface — but inside SQL Server, they trigger a complex chain of storage‑engine behaviors that can dramatically affect performance, concurrency, fragmentation, and long‑term maintainability. Whether your tables are heaps or clustered indexes, DML operations behave very differently under the hood, and understanding those differences is essential for building predictable, high‑performance systems.
This session takes you deep into the mechanics of DML in SQL Server. We’ll explore how INSERTs allocate pages and extents, why heaps generate forwarding records, and how clustered indexes maintain logical order through page splits and page merges. You’ll learn how updates can silently become deletes + inserts, why wide rows cause unexpected IO, and how delete patterns influence ghost records, version store usage, and index fragmentation.

Intermediate to Advanced. Attendees should be familiar with SQL Server storage structures, indexing fundamentals, and execution plans. No prior knowledge of allocation internals or log‑writing mechanics is required — these concepts will be introduced during the session.