Blog | Madeira Data Solutions

The Curious Case of the Missing Histogram

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.

DBA

Guy Glantser

2 days ago4 min read

Remodeling - Improving Concurrency

Improving Concurrency: Data Modeling with Vertical Partitioning Reducing locking, blocking, and deadlocks in wide tables by distributing updates across one-to-one related tables Not long ago, I worked with a customer who was experiencing persistent blocking and occasional deadlocks in one of their core systems. The application itself wasn’t new, but over the years it had grown significantly. New features had been added, more processes were interacting with the database, and n

mohammed884

May 133 min read

סדר העמודות באינדקס

כבר הרבה מאוד שנים שה-execution plans כוללים המלצות לאינדקסים, וכך גם כלים כמו sys.dm_db_missing_index_details, ובימינו התווספו להם כלי AI שאמורים להחליף אותנו או את שיקול דעתנו. הבעייה העיקרית עם כל הנ"ל שהם נותנים המלצות טובות למקרה ספציפי, אבל לנו יש עדיין את שיקול הדעת כיצד להימנע מריבוי אינדקסים, וכיצד לבנות אותם כך שיביאו תועלת גם במקרים אחרים; ובמקרה השני עוסק הפוסט הזה. נכין קודם כל את רשימת החומרים: Use tempdb Go Drop Table If Exists Bad; Select 1 N, * Into Bad F

Geri Reshef

Apr 255 min read

Cascading Foreign Keys: I Was Against Them… Until I Finally Understood Why

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.

DBA

Guy Glantser

Mar 243 min read

When Statistics Stay Empty Forever: A Hidden Edge Case with Empty Tables

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.

DBA

Guy Glantser

Mar 53 min read

Change X-Axis values based on slicer user selection

Want your Power-BI visual to automatically switch between different hierarchies based on slicer selection – without drill mode or extra clicks? In this post, I’ll show a simple DAX pattern that makes your X-axis dynamic and user-friendly.

Data Analysis