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Category: Administration

Scheduling Azure ML Compute Instance Start-Up and Shut-Down

Published 2022-01-24 by Kevin Feasel

I have a post correcting a statement I made before:

The single biggest problem I have with compute instances is that there is no auto-stop functionality to them. This is really frustrating because you’re paying for that virtual machine like you would any other, so if you forget to turn it off when you go home for the weekend, it’ll cost you. I wish there were a built-in option to shut off a compute instance after a certain amount of inactivity. Instead, you’ll need to start and stop them manually.

It turns out that you can and so I wanted to write a post to correct the record.

Click through to see how you can do this. You can bet that I’ve got it enabled now.

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Negative Blocking Session IDs

Published 2022-01-24 by Kevin Feasel

Bob Dorr explains what those negative session IDs actually mean:

SQL Server may report a blocking session id as a negative integer value. SQL Server uses negative sessions ids to indicate special conditions.​​ 

Click through for the table. Bob also includes information on -5, the “any task/session can release the latch” scenario. This also covers information on the latches themselves and is worth keeping around in case you run into an issue at some point.

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Monitoring Power BI Queries with Log Analytics

Published 2022-01-24 by Kevin Feasel

Chris Webb continues a series on using Log Analytics:

It’s actually very easy to build a simple KQL query to look at query activity on your datasets: you just need to look at the QueryEnd event (or operation, as its called in Log Analytics), which is fired when a query finishes running. This event gives you all the information you need: the type of query (DAX or MDX), the duration, the CPU time, the query text and so on. The main challenge is that while you also get the IDs of the report and visual that generated the query, you don’t get the names of the report or visual. I wrote about how to get a list of visual and report IDs here and here, but how can you use that information?

Read on to see how.

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Understanding the Transaction Log

Published 2022-01-21 by Kevin Feasel

Paul Randal has a new series:

With this post, I’m starting an occasional series on the transaction log and how it works and should be managed, and I’ll touch on all the problems above over its course. In this post, I’ll explain what logging is and why it’s required.

Basic Terminology Around Logging

When I’m talking about any mechanism in SQL Server, I find there’s a chicken-and-egg problem where I need to use a word or phrase before I’ve explained it. To avoid that problem in this series, I’m going to start by explaining some terminology that needs to be used when discussing logging, and I’ll expand on many of these terms as the series progresses.

This post starts off with some of the basics and it’s always good to get the occasional refresher on the basics.

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Measuring Cost Threshold for Parallelism Effectiveness

Published 2022-01-20 by Kevin Feasel

Michael Swart gets out the ruler:

The configuration setting cost threshold for parallelism has a default value of 5. As a default value, it’s probably too low and should be raised. But what benefit are we hoping for? And how can we measure it?

The database that I work with is a busy OLTP system with lots of very frequent, very inexpensive queries and so I don’t like to see any query that needs to go parallel.

What I’d like to do is raise the configuration cost threshold to something larger and look at the queries that have gone from multi-threaded to single-threaded. I want to see that these queries become cheaper on average. By cheaper I mean consume less cpu. I expect the average duration of these queries to increase.

Read on for Michael’s results, and I appreciate somebody actually testing and measuring rather than pulling a number from a hat.

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Finding your SQL Server Product Key

Published 2022-01-19 by Kevin Feasel

I share a tale of woe:

I was working on an upgrade recently, trying to move from SQL Server 2016 to SQL Server 2019. I wanted to perform an upgrade in-place on an Azure VM, but needed to get the product key. There are a few places where you can find Powershell functions to get this product key, with Ryan @ Ryadel’s post being the most well-known. That method covers versions from SQL Server 2005 through 2014 (if you follow the notes in the blog post), but breaks on 2016.

Click through for a script which works for SQL Server 2016 and later.

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The Benefits of Indirect Checkpoints

Published 2022-01-19 by Kevin Feasel

Aaron Bertrand explains why it’s probably a good idea to enable indirect checkpoints:

At Stack Overflow, the upgrade to SQL Server 2019 was not as smooth as expected. It introduced long recovery times and high CPU on a secondary, during synchronization activity after failover, patching, and network connectivity testing. This symptom wasn’t present during similar activities and workloads under SQL Server 2017.

Aaron points out that if you have databased created in older versions of SQL Server, enabling indirect checkpoints can provide a performance boost to certain activities around log writing., including backup times.

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Automating Azure SQL DB Maintenance with Data Factory

Published 2022-01-18 by Kevin Feasel

Hiten Bhavsar works around the lack of SQL Agent:

As we know, it’s crucial that you run Database maintenance regularly in order to keep your database performance up with the latest statistics and healthy indexes, here we provide another way to schedule this job using Azure Data Factory; this can be done on a scheduled time interval weekly/bi-weekly/monthly.

Click through for the process and try not to think too hard about this secretly being maintenance plans all over again.

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Cannot Open User Default Database

Published 2022-01-17 by Kevin Feasel

David Alcock backs out of a problem:

This error isn’t to do with my login as such, it’s still there with sysadmin role membership so I don’t have to do anything too drastic like restarting SQL Server with the -m or -f startup parameters and recreate it. The error message is telling me that my logins default database cannot be opened, which is more than likely because I’ve deleted it.

Click through to see how David got out of this issue. This is a big part of why I highly prefer not to change the default database from master for logins..

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