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Curated SQL Posts

Analyzing Power BI Refresh Performance with Log Analytics

Published 2023-07-17 by Kevin Feasel

Chris Webb starts a new series:

If you’re tuning refresh for a Power BI Import mode dataset one of the areas you’ll be most interested in is throughput, that is to say how quickly Power BI can read data from the data source. It can be affected by a number of different factors: how quickly the data source can return data; network latency; the efficiency of the connector you’re using; any transformations in Power Query; the number of columns in the data and their data types; the amount of other objects in the same Power BI dataset being refreshed in parallel; and so on. How do you know if any or all of these factors is a problem for you? It’s a subject that has always interested me and now that Log Analytics for Power BI datasets is GA we have a powerful tool to analyse the data, so I thought I’d do some testing and write up my findings in a series of blog posts.

In the first post, Chris gives us an overview of information available and provides one way to query it.

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Optimizing for Readability or Performance

Published 2023-07-14 by Kevin Feasel

Hugo Kornelis talks trade-offs:

But I wanted to contribute anyway. So here is a recent example of code that probably would have made me feel a way if I had been the type of person that gets emotional over code. Or put differently, here is the story of how I gained performance by reducing readability and maintainability.

For the record, and to prevent confusion, I am not going to name actual customers, nor name the ERP system used, and the description I give is highly abstracted away from the original problem, and heavily simplified as well. I describe the basis of what the issue was with the code I encountered and how I fixed it, but without revealing any protected information.

My internal motto is:

  • Start with simple, readable code
  • Move to more complex, faster performance in spots which are necessary
  • Document why the code is more complex with illuminating comments, so that way a future developer (including future you) won’t say, “What was this yokel thinking, doing this complicated thing when there’s an easy approach like this?”
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Using the Azure Data Factory Self-Hosted Integration Runtime

Published 2023-07-14 by Kevin Feasel

Chen Hirsh hosts a runtime:

In Azure data factory (ADF), An integration runtime is a compute resource to run your pipelines on. When you run an application on your computer, it uses the computer resources, such as CPU and memory, to run its tasks. When you run activities in a pipeline in ADF, they also need resources to do their job, like copying data or writing a file, and these are provided by the integration runtime.

When you create an instance of ADF, you get a default integration runtime, hosted in the same region that you created ADF in. If you need, you can add your own integration runtimes, either on Azure, or you can download and install a self-hosted integration runtime (SHIR) on your own server.

Read on to understand when you would want to use a self-hosted integration runtime and the process to do so. This SHIR also applies to Synapse pipelines and is one of the few ways to move data out of a Synapse workspace with data exfiltration protection enabled.

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Security Concepts: Who? and Where?

Published 2023-07-14 by Kevin Feasel

Kenneth Fisher is trying to figure out where he left his keys:

I was having a conversation with some friends the other day and Jen McCown (blog|twitter) asked about SQL Server security references and “What’s something that’s really difficult in SQL Server Security.” As happens sometimes I started thinking about this in the back of my head and I realized something. The two absolute hardest things that people run into with security (at least in my ever so humble opinion) are

  • Who: or Who am I when I try to access a resource?
  • Where: or Where am I when I try to access a resource? And Where is that resource?

Read on for Kenneth’s thoughts.

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IS DISTINCT FROM in Snowflake

Published 2023-07-13 by Kevin Feasel

Kevin Wilkie remains distinct:

Now, the more fun – “new-ish” – version of the DISTINCT keyword.

Let’s take two values – A and B. Let’s define A = 7 and B = 2.

Snowflake will allow you to ask if A IS DISTINCT FROM B. Thankfully, in this case, it is.

Click through to see how this works. Also note that this syntax is available in SQL Server 2022.

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Data Validation in Excel from a DAX Query

Published 2023-07-13 by Kevin Feasel

Gilbert Quevauvilliers builds a data validation tool in Excel:

I had a requirement where the customer wanted to make sure that the right user could only see the colour from the stock item assigned to them. Essentially using the Excel file for Row Level Security.

For the Row level security to work correctly it required the colour name to be an exact match.

For me to ensure that this would happen, I wanted to make sure I could get the data from my Power BI dataset, and then using the Excel data validation make sure that the user could either type in the value 100% correct or pick it from the drop-down list.

There are quite a few steps, but I can see business people being happy about the final outcome.

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Creativity, Learning from Code, and the APPLY Operator

Published 2023-07-13 by Kevin Feasel

Rob Farley covers one of my favorite operators:

SQL Server 2005 was released, of course, in 2006, and I had been running the Adelaide SQL Server User Group since September 2005. Information about the new features had been coming through, and I’d been at TechEd Australia 2005 – my first since 1999. I was still an application developer at the time (well, a manager, but still getting my hands dirty), but saw the data as the most important part of my applications. When the T-SQL enhancements in SQL Server 2005 came through, there were two things that caught my eye (I know they were available in Oracle before SQL Server, but I was focusing more on the Microsoft platform by then). They were the OVER clause, and APPLY.

This is all part of a broader story about reading code to learn from it.

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Users and Role Members for Azure SQL Databases

Published 2023-07-13 by Kevin Feasel

Peter Schott makes a list:

I ran into a concern to quickly audit all current users and role members for a set of Azure SQL databases, spread across multiple resource groups. Without an easy CMS concept or a way to quickly loop through an unknown set of servers, resource groups, and databases, that can be a little challenging. I have an account to use that should have access to all databases (but doesn’t) so put together some PowerShell that I could run locally to get that information and send the results to Excel.

Click through for a SQL script to get the data and a Powershell script to run this for each database and export the results into different tabs in Excel.

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