13Nov 2023 by Grant Fritchey No Comments

Query Store Reports Time Intervals

SQL Server
A great question came up over at DBA.StackExchange regarding the query store reports time intervals: How can SQL Server's Query Store Reports show data for minute-length intervals, when "Statistics Collection Interval" is set to 1 hour? I was intrigued because it's not something I had thought about at all. How Does the Report Decided on Time? The first thing you need to know is that all performance information inside Query Store is aggregated. By default, the aggregation interval is 60 minutes. You can adjust that up or down (although, I wouldn't recommend making it too granular, you'll see a massive increase in storage size). It's aggregated because trying to capture every execution of every query, as anyone who has done it using Extended Events knows, is expensive and has a…
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20Feb 2023 by Grant Fritchey No Comments

What Happens On AWS RDS?

AWS, RDS
I was talking with some developers from my team about monitoring, and I said, "We all use the same tools," referring to other monitoring software. Then, it hit me. How is AWS collecting monitoring data on it's RDS servers, specifically, the SQL Server instances. So, I set out to determine what happens on AWS RDS when it comes to the native monitoring. The Setup This part should be as obvious as it is easy. I'm going to use Extended Events. I've written before about how AWS RDS supports Extended Events, so I won't repeat all that here. I'll just leave you with the session I'm running to see what happens on AWS RDS: CREATE EVENT SESSION [ExEventTesting] ON SERVER ADD EVENT sqlserver.rpc_completed, ADD EVENT sqlserver.sql_batch_completed ADD TARGET package0.event_file (SET filename…
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11Nov 2022 by Grant Fritchey 2 Comments

SQL Server 2022 Query Performance Tuning

SQL Server
If you're interested in getting a digital copy, my brand spanking new book is now available here. It's in the intro, but let me tell you a little bit about the new book. It's really new. Some of the older versions of the book were simply updated, a bunch of changes to most chapters, a couple of new chapters, fixes for old mistakes, ta-da, new book. Not this time. This time, I rewrote it all. From scratch. Now, some of the chapter titles are the same. Quite a few of the examples are the same (if code illustrates something successfully, I'm reusing it). However, overall, it's a brand new book. There's a lot of new material too. The last update was for SQL Server 2017. There has (almost) been two…
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03Oct 2022 by Grant Fritchey 2 Comments

Function Vs. Performance

SQL Server
Recently I was looking through DBA.StackExchange when I saw a pretty simple question that I decided to answer. I went off, set up a test database and some test tables and quickly wrote a query to answer the question. I got it all formatted pretty and was on my way to post it when I saw that another answer was already there. Yeah. Identical to mine. Almost line for line. Well, nuts. I know. I'll write a blog post. The Setup The original poster had two tables that, frankly, are badly designed. However, they share enough data that they are "related" if not relational. Here's the code: CREATE DATABASE Testing; GO USE Testing; GO CREATE TABLE Table_A ( ID INT IDENTITY(1, 1), Score INT ); CREATE TABLE Table_B ( FromPoint…
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15Aug 2022 by Grant Fritchey 1 Comment

Distributed Replay: The Little Engine That Almost Could

SQL Server
Honestly, sincerely, no kidding, I love Distributed Replay. Yes, I get it. Proof positive I'm an idiot. As we needed proof. To be a little fair to me, I love what Distributed Replay could have been, with a little more love. However, fact is, it's on the deprecation list for 2022. Which means, what minimal amount of love, if any, that Microsoft was giving to it, it's all gone, forever. Unlike the Little Engine That Could, turns out that Distributed Replay was the Little Engine That Almost Could, But Didn't. Really Didn't. Let's discuss it a bit. Distributed Replay The concept is wonderful. Capture a bunch of queries from your production system. Replay them on a non-production system for testing. Add in the idea of being able to chain together…
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09Feb 2022 by Grant Fritchey 6 Comments

SQL Server, PostgreSQL and the Future

PostgreSQL, SQL Server
This is just a quick note to talk about the future, mine, yours and this blog. First, I'm not abandoning SQL Server. I'm actively working on a revision of the query performance tuning book (something I should be working on instead of writing this post). SQL Server is my first, and best, database love. We're not going anywhere, SQL Server and I. You can expect more posts on SQL Server, query tuning, execution plans, DevOps, community, #sqlfamily, and everything I've blogged about for the last, ooh, 14 years next month. Second, our family is growing. Just like when a family brings home a new baby, well, I'm adding another database. It doesn't mean I don't love my first database. I still do. We're just going to ALSO be talking about…
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03Jan 2022 by Grant Fritchey 4 Comments

Identifying Recompile Causes

SQL Server
Strictly speaking, a recompile isn't really a performance tuning problem. In fact, a lot of time, recompiles are desired because they reflect changes in statistics which are likely to need a new plan. However, you can get really excessive levels of recompiles because of a variety of different issues. So, identifying the causes can be a pain. Here's one way to get it done. Extended Events for Recompile Causes You knew I was going there. Seriously though, we know that, since SQL Server 2005, all recompiles are at the statement level (unless you call for a recompile of a procedure or create that proc with a RECOMPILE hint). So, capturing the recompiles and getting grotty on the details means capturing statements. Understand that this can be expensive, especially in terms…
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29Nov 2021 by Grant Fritchey No Comments

Get SQL Server 2022 Now: It’s Called Azure

Azure, SQL Server
If you're like me, your palms went into a cold sweat to get your grubby fingers on the bits for SQL Server 2022 a few nanoseconds after you heard the announcement. Well, you might be waiting a while. As will I. However, I really do want to start experimenting with some of the functionality right now. If you do to, then join me at Azure SQL Database. Azure SQL Database as a Preview for SQL Server 2022 Yeah, I know it's not the same. I get it. You have a need to run this stuff on big iron, not virtual, and certainly not in the cloud. Still, you want to learn, right? Tons of the new functionality is either already in Azure or incorporates Azure functionality. You can get started…
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06Jul 2021 by Grant Fritchey No Comments

Permissions Needed To Force Plans in Query Store

SQL Server
I was recently asked what permissions were needed to force plans in query store. I'm sure I knew at one point, but at the moment I was asked, I couldn't remember to save my life. So, I went and looked it up. In the interest of sharing, especially for the poor person who I left hanging, here's what I found. Permissions in Query Store Look through the blog, you'll find I'm pretty enamored with Query Store. I even contributed to a book on the topic (a little, it was almost all Tracy's work on that book, I just helped out). I haven't addressed security and Query Store. You do need to think about security in Query Store. For example, should you give read access to Query Store to your dev…
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