A 7-million-row table. A clustered primary key. Auto-update statistics enabled. Yet the index statistics had never been updated, and the histogram was missing. At first, it looked like a SQL Server bug. The real explanation was much more surprising—and reveals an important detail about how the optimizer decides when a histogram is actually needed. Along the way, I'll also cover a recent enhancement to Ola Hallengren's maintenance solution inspired by this edge case.

For years, I avoided cascading foreign keys without fully understanding why. Then I discovered what SQL Server really does under the hood - escalating locking behavior to guarantee consistency. Combine that with missing indexes, and a simple delete can lock entire tables. Here’s why ON DELETE CASCADE deserves more respect than we give it.

Many SQL Server DBAs rely on automated statistics maintenance solutions, but they might be unaware of a corner case that can cause statistics to remain empty forever.