Blogs

Statistics in SQL Server are simple in theory: they help the optimizer estimate how many rows a query might return. In practice? Things get weird fast. Especially when you start filtering on multiple columns, or wondering why the optimizer thinks millions of rows are coming back when you know it’s more like a few hundred thousand. In this post, I’ll walk through examples using single-column, multi-column, and filtered statistics—and show where estimates go off the rails, when they get back on track, and why that doesn’t always mean you need to update everything with FULLSCAN.

All Eyes on the Wrong Problem: How Mitigations Distract from Real Performance Pain

By Kendra Little in SQL Server

April 6, 2025

The biggest lesson I’ve learned from helping folks manage data in Azure is this: if you’ve got a truly terrible problem you’d rather people didn’t notice, a great way to hide it is by educating your support staff and users about something bad but not AS terrible— something with a small mitigation—and constantly refocusing them on that.

The user base— and even your own support staff— will think that anyone who talks about the bigger issue just doesn’t understand how to fix the “known” problem.

This is the story of Azure General Purpose storage for Azure SQL Managed Instance and Azure SQL Database.

100 Things I Hate About Views: Undeclared Data Types in Columns

By Kendra Little in SQL Server

March 14, 2025

Views let you do dumb things by accident in SQL Server. Then they make you have to think way too hard to fix them.

What the Decline of Sql Server Quality means for Developers and DBAs

By Kendra Little in SQL Server

March 10, 2025

“Is it just me, or is SQL Server quality slipping?”

I asked myself that question for couple/few years until I faced up to it: SQL Server is well into a period where Microsoft investment is waning, and Microsoft regularly isn’t able to deliver the features they promise.

AI will eliminate DBA Jobs faster than you think

By Kendra Little in SQL Server

March 2, 2025

I listened to “Surviving the A.I. Endgame” this weekend and realized: I’ve become one of the believers that AI advances are very likely to completely change tech and knowledge roles as we know them over the next 10 years. This is going to dramatically shrink the workforce across MANY roles (and many of those impacted will be outside of the tech sector). It isn’t that people won’t be needed anymore, but far fewer people will be needed.

How to Stop SSDT / Database Projects / SQLPackage from Modifying Database Options

By Kendra Little in SQL Server

February 13, 2025

SQL Server’s free state-based version control tooling was introduced under the “Data Dude” brand, then became known as “SQL Server Data Tools” (SSDT). Its extension for the (now dying) Azure Data Studio IDE is called “SQL Database Projects.” If you need to find documentation, you often need to know to search for specific component names like SQLPackage.exe, which is a command line utility used to deploy SSDT Projects AKA SQL Database Projects.

Buyer Beware: Azure SQL Managed Instance Storage is Regularly as Slow as 60 Seconds

By Kendra Little in SQL Server

December 18, 2024

What are your stories of unbelievably bad performance from cloud vendors? I’ll go first. For years, Azure SQL Managed Instance’s General Purpose Tier has documented “approximate” storage latency as being “5-10 ms." This week they added a footnote: “This is an average range. Although the vast majority of IO request durations will fall under the top of the range, outliers which exceed the range are possible.” How approximate is that 5-10 milliseconds, you might wonder?

Query Hash Values are Meaningless in SQL Server: They May be Reset to be the Same Value as the Query Plan Hash

By Kendra Little in SQL Server, Query Store

November 24, 2024

This is the worst bug I’ve found in SQL Server to date. Previously, my top find was SQL Server Online Index Rebuild sometimes happens offline without warning. This one has taken top slot because it makes my life more difficult on a daily basis. Background: SQL Server generates a query_hash for each query. This is stored in sys.query_store_query and it’s one of the primary ways you can identify what a query is across different Query Stores, or even the same Query Store over time, as surrogate query_id values get reset if Query Store is cleared or data ages on.

What Is the CPU Wait in Datadog SQL Server Monitoring? How does it Compare to Waiting on CPU?

By Kendra Little in SQL Server

November 21, 2024

I use Datadog on a regular basis, and I’m a pretty huge fan. The monitoring pack for SQL Server (and its PAAS variants) is still pretty rudimentary, but it evolves regularly. That’s NOT what I’m a fan of, though. What makes me a raving fan is the flexibility of Datadog’s notebooks and dashboards, combined with the ability to create all sorts of custom metrics and monitors. There are always things in SQL Server monitoring packs that I have strong opinions about.

How to Survive Opening A Microsoft Support Ticket for SQL Server or Azure SQL

By Kendra Little in SQL Server

September 23, 2024

Asking Microsoft for support for SQL Server or Azure SQL is a lousy experience these days. This is true whether you are using a cheaper service tier or the more expensive support tier formerly known as “Premiere Support.” Either way, I’ve found the same issues: as the person requesting support, I must know a whole lot about the root cause of my problem and how to solve it, or my request will be dismissed with misinformation. I need to have data and metrics that back up my claims in order to get the ticket escalated to someone who can help, and I will need to provide those receipts three or four times. Once something is escalated to the Product Group, I may get a helpful response, but it will generally take a while. If I’m not engaged directly with the Product Group and the answer is being relayed through a lower support tier, it often won’t make much sense.

These issues don’t happen due to bad work ethics or personal failings of support workers. These are good humans, who are trying their best! The problem is worse, because it’s systemic.

Comparing Single Column, Multi-Column, and Filtered Statistics in SQL Server

All Eyes on the Wrong Problem: How Mitigations Distract from Real Performance Pain

100 Things I Hate About Views: Undeclared Data Types in Columns

What the Decline of Sql Server Quality means for Developers and DBAs

AI will eliminate DBA Jobs faster than you think

How to Stop SSDT / Database Projects / SQLPackage from Modifying Database Options

Buyer Beware: Azure SQL Managed Instance Storage is Regularly as Slow as 60 Seconds

Query Hash Values are Meaningless in SQL Server: They May be Reset to be the Same Value as the Query Plan Hash

What Is the CPU Wait in Datadog SQL Server Monitoring? How does it Compare to Waiting on CPU?

How to Survive Opening A Microsoft Support Ticket for SQL Server or Azure SQL

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