18Dec 2017 by Grant Fritchey 8 Comments

Query Store Wait Statistics with sys.query_store_wait_stats

Azure, SQL Server 2017
The second best thing to questions that people ask is when I sit down to write a book. It's so easy to miss things in the day-to-day grind of doing work. Then, late at night, you're working on a chapter, so you read up on the documentation to ensure that you're not missing anything. Of course, then you find, yes, you are missing something. In my case, sys.query_store_wait_stats. sys.query_store_wait_stats. If you follow the link above, it'll give you what you need to know, but, I figured I'd provide a little more clarity because I think there are some pitfalls in using this data. I love Query Store (do a search to see all the exploration I've done with it). One of my favorite things is the time intervals. It breaks…
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15Aug 2016 by Grant Fritchey 5 Comments

Query Store, Force Plan and Dropped Objects

Azure, SQL Server 2016
I love the Query Store. Seriously. It’s a huge leap forward in the capabilities of Azure SQL Database and SQL Server in support of performance monitoring and query optimization. One of my favorite aspects of the Query Store is the ability to force plans. Frankly though, it’s also the scariest part of the Query Store. I do believe that plan forcing will be one of the most ill-used functions in SQL Server since the multi-statement table-valued user-defined function (don’t get me started). However, unlike the UDF, this ill-use will be because of poor understanding on the part of the user, not a fundamental design issue. No, plan forcing and the Query Store are very well constructed. Let me give you an example of just how well constructed they are. Let’s…
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09Aug 2016 by Grant Fritchey 4 Comments

Azure SQL Database For Your First Database

Azure
This is post 8 supporting  Tim Ford’s (b|t) initiative on #iwanttohelp, #entrylevel. Read about it here. In post #6, I talked about Azure SQL Database as one of the choices you have when you're picking the type of SQL Server instance you want to run. I want to expand on why you should be considering moving into Azure SQL Database at the start of your career and some of the important differences you'll have to be aware of as you get going. Since you are right at the start of your career, you may as well plan on maximizing the life of the knowledge and skills you're building. By this, I mean spend your time learning the newest and most advanced software rather than the old approach. Is there still work for people who only know…
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06Jun 2016 by Grant Fritchey 2 Comments

Elastic Query in Azure SQL Database and Views

Azure
The question came up, how do the constructs necessary for Elastic Query within Azure SQL Database affect your ability to create views that join across databases. Since I haven't tested this myself, and I haven't seen anyone else doing anything with it yet, I decided to set up a test. I recreated my cross database queries using the scripts posted here. Let's create a view: CREATE VIEW dbo.JoinedView AS SELECT dt.Val, dt2.Val AS Val2 FROM dbo.DB1Table AS dt LEFT JOIN dbo.DB2Table AS dt2 ON dt2.ID = dt.ID; If I run the query, I get back results. Done. We can create views that join between Azure SQL Databases... But, views are all about masking right? What if I wanted to change the name of the table on my database. Could I…
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16May 2016 by Grant Fritchey 8 Comments

Query Store, Forced Plans, and New Plans

Azure, SQL Server 2016
I love questions. I recently received one about new plans in the Query Store (available in Azure SQL Database now and in SQL Server 2016 after June 1). Let's say you have selected a plan that you want to force. You set it up. Now, let's say the plan ages out of cache or even goes through a recompile. During the recompile, due to out of date statistics or skew in the statistics, you would, under normal circumstances, get a new plan. However, with Query Store and plan forcing, the plan that's going to be used is the plan that is being forced. But, does that other plan, the one not used, get stored in Query Store? I have no idea. Let's find out. The Setup To start with, a small stored procedure…
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25Mar 2016 by Grant Fritchey 4 Comments

Happy Dance!

Azure
I'm all like: Because I saw this on an eval: I've been trying to ramp up to take advantage of my MSDN subscription and haven't known where to start. I don't have that excuse now. And then I was all like: Because: We are moving a lot of stuff to Azure. I had some experience using SQL Azure but felt blind when doing it. Grant made me feel better about my experience as it is very much like he explained. and: Azure is becoming a REAL THING. It's nice to get such a great primer of it. <calming down> I'm quite pleased to see that Azure sessions are getting such an improved reception. <SQUEEE>
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21Mar 2016 by Grant Fritchey 56 Comments

Cross Database Query in Azure SQL Database

Azure
You can't query across databases in Azure SQL Database... or can you? Let's check. I've created two new databases on an existing server: I've created two tables on each respective database: CREATE TABLE dbo.DB1Table ( ID INT IDENTITY(1, 1) NOT NULL PRIMARY KEY, Val VARCHAR(50) ); CREATE TABLE dbo.DB2Table ( ID INT IDENTITY(1, 1) NOT NULL PRIMARY KEY, Val VARCHAR(50) ); Now, let's query the DB2 table from the DB1 database: SELECT * FROM DB2.dbo.DB2Table AS dt; And here's the lovely error message: Msg 40515, Level 15, State 1, Line 35 Reference to database and/or server name in 'DB2.dbo.DB2Table' is not supported in this version of SQL Server. So, like I said, you can't do three part name cross-database queries in Azure SQL Database... oh wait, that's not quite what I said…
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29Feb 2016 by Grant Fritchey 4 Comments

Wait Statistics in Azure SQL Database

Azure, T-SQL
You need to be aware that you're going to see differences when you're working with Azure SQL Database when it comes to wait statistics. If you're running a v12 Azure SQL Database (and if you're not, go fix it), you can run a query against sys.dm_os_wait_stats. Here's the output for the TOP 10 waits ordered by wait time on one of my databases: Everything you're used to seeing, right? Well... not quite. This is Azure SQL Database. So, let's use sys.dm_db_wait_stats, a DMO that is only available within Azure. This lists waits by database. The TOP 10 here are: You'll notice that these results are wildly different from those above. What we're looking is largely a server versus a database, but not completely. I mean that sys.dm_os_wait_stats is showing the waits for the…
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18Feb 2016 by Grant Fritchey 4 Comments

Azure SQL Database Error

Azure
I was on SQL Cruise where I was scheduled to present a session on Azure SQL Database. I recorded all my demonstrations before we went to sea, but, I planned to attempt to try live demo's. Yeah, yeah. Well, anyway, I got a unique error when I attempted to connect: Forced connection closes from remote host That's a partial message from the whole error. I don't have a good screen capture. I wasn't able to find anything on it through Ging searches, but this week I was at Microsoft for a training course on Azure. I asked the room. The rough answer is (paraphrasing): The IP address I was attempting to connect from is not is not on the approved list Interesting. I didn't realize there were blackout zones. The really…
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25Jan 2016 by Grant Fritchey 7 Comments

Finding Your Query in Query Store

Azure, SQL Server 2016, T-SQL
Query Store is pretty amazing. I'm loving working with it. I think it's likely to change how query tuning will be done in the future. Lots of people are probably going to just use the reports and tools in SQL Server Management Studio. However, a pretty healthy chunk of us will start using the system views in order to programmatically access the information stored in Query Store. One of the first things you're going to want to do is track down your query. The primary views you'll want are sys.query_store_query and sys.query_store_query_text. They join together based on the query_text_id. Let's take four scenarios and see if we can retrieve the correct query. First up, an ad hoc query: SELECT e.NationalIDNumber, p.LastName, p.FirstName, a.City, bea.AddressTypeID FROM HumanResources.Employee AS e JOIN Person.BusinessEntityAddress AS…
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