Press "Enter" to skip to content

Curated SQL Posts

Another Number Series Generator Solution

Published 2021-04-15 by Kevin Feasel

Itzik Ben-Gan reviews Paul White’s solution to the number series generator challenge:

I love Paul White’s work. I keep being shocked by his discoveries, and wonder how the heck he figures out what he does. I also love his efficient and eloquent writing style. Often while reading his articles or posts, I shake my head and tell my wife, Lilach, that when I grow up, I want to be just like Paul.

When I originally posted the challenge, I was secretly hoping that Paul would post a solution. I knew that if he did, it would be a very special one. Well, he did, and it’s fascinating! It has excellent performance, and there’s quite a lot that you can learn from it. This article is dedicated to Paul’s solution.

This is an elite pair-up and well worth your time to review in detail.

Comments closed

Updating or Creating a Measure for Power BI PPU without Full Publication

Published 2021-04-15 by Kevin Feasel

Gilbert Quevauvilliers follows up:

Following on from my previous blog post How to complete granular deployment of Power BI Desktop changes to the Power BI Service (Using PPU), I want to also show how to update or create a measure in my dataset, where I can deploy this via ALM Toolkit.

This now saves me from doing the following tasks previously:

– Time taken to refresh the PBIX file so that the data is up to date.
– Re-uploading my PBIX.
– If configured re-creating the incremental refreshing
– Time and effort to upload and wait for dataset refresh.
– Quick updates to my dataset.

I will not have to worry about saving my PBIX file, file and if configured re-creating the incremental refreshing. This saves me a lot of time and effort.

Read on to see how.

Comments closed

Reading from Oracle without the Oracle Client

Published 2021-04-15 by Kevin Feasel

Emanuele Meazzo was in a bind:

If you read my previous article on how to configure a Linked server to Oracle , you know that I feel like someone is plotting to keep the topic of how to get our precious data outside of the Oracle ecosystem as obscure as possible out of the oracle circle
Fear not! I’m here to get you all the info in order to get data from Oracle Database via Powershell, in a native high-performance way, allowing you to create a multithreaded, reliable and connected ETL flow to feed a data warehouse from Oracle data, like the owner of this blog, or just move quickly some data from one place to another, programmatically, whatever it’s your need.

I support any effort to get data away from Oracle. Click through for the script and an explanation of each step.

Comments closed

More About Default Parameter Values in Powershell

Published 2021-04-15 by Kevin Feasel

Jeffrey Hicks follows up on a prior post:

Last week I shared a little nugget about making PowerShell life easier by using the built-in variable, $PSDefaultParameterValues. This is a special hashtable where you can define default parameter values for any PowerShell command. This means any PowerShell script or function that has defined parameters AND uses [cmdletbinding()]. If you have a simple function that only uses a Param() block, $PSDefaultParameterValues won’t work for that function. I recommend that all PowerShell functions use [cmdletbinding()] so hopefully, this won’t be an issue. Since I received some positive feedback and a few questions on the previous post, I thought a quick follow-up might be in order.

Read on for additional useful information regarding $PSDefaultParameterValues.

Comments closed

Fun with Multiple Indexes

Published 2021-04-15 by Kevin Feasel

Erik Darling makes a fairly rare multi-index sighting:

Notice! Both of our nonclustered indexes get used, and without a lookup are joined together.

Because the predicates are of the inequality variety, the join columns are not ordered after each seek. That makes a hash join the most likely join type.

I’ve always had this belief that there are probably more cases in which multi-index solutions are useful than the SQL Server optimizer gives us. This belief may be irrational.

Comments closed

Superkeys

Published 2021-04-14 by Kevin Feasel

Kevin Wilkie knows that not all keys wear capes:

Well, that’s because we sometimes need different ways to describe what we’ve got going on. Of the four different types of keys we’ve discussed so far, they are all different enough that we need to differentiate them and be able to explain what the differences are. For the rest of the keys that we’ll go through today, the same idea exists. They are close to the others but different enough that there is a need for another name for that type of key.

There is a super key.

Read on to learn what a superkey is. That will put you one quarter of the way to understanding Boyce-Codd Normal Form: a relational variable is in Boyce-Codd Normal Form if and only if all functional dependencies have superkey determinants.

Comments closed

Common Query Plan Patterns for Joins

Published 2021-04-14 by Kevin Feasel

Erik Darling has a new mini-series. First up is degrees of parallelism and bitmaps:

But wait! This query runs at DOP 4. You can tell by looking at the number of executions.

Who runs queries at DOP 4?

Fools.

This DOP goes up to 11.

Next, Erik versus equality predicates:

But not every query has an available equality join predicate. For various reasons, like poor normalization choices, or just the requirements of the query, you may run into things like I’m about to show you.

If there’s a headline point to this post, it’s that joins that don’t have an equality predicate in them only have one join choice: Nested Loops. You cannot have a Hash or Merge join with this type of query. Even with the best possible indexes, some of these query patterns just never seem to pan out performance-wise.

Read on for the implications of this, as well as techniques to improve performance.

1 Comment

Importing Data from ADLS Gen2 into Power BI

Published 2021-04-14 by Kevin Feasel

Chris Webb summarizes a significant amount of work:

Over the last few months I’ve written a series of posts looking at different aspects of one question: what is the best way to import data from ADLSgen2 storage into a Power BI dataset? For example, is Parquet really better than CSV? Should you use Azure Synapse Serverless? In this post I’m going to summarise my findings and offer some recommendations – although, as always, I need to stress that these are the conclusions I can draw from my test results and not the absolute, incontrovertible “Microsoft-says” truth so please do your own testing too.

Read on and check it out for yourself.

Comments closed

Using Notebooks in Azure Machine Learning Studio

Published 2021-04-14 by Kevin Feasel

Lina Kovacheva takes us through the process of working with notebooks in Azure Machine Learning Studio:

I discovered Jupiter notebooks not that long ago, but the more I use them the more I see how powerful they could be. For those of you who are not familiar whit Jupiter Notebook: It is an open-source web application where you can combine code, output, visualizations and explanatory text all in one document allowing you to write a code that tells a story. Now that you have an idea of what Jupiter notebook is I will walk you through how you can use it in Azure Machine Learning Studio.

Click through for the process. One advantage to notebooks in an environment like Azure ML over Azure Data Studio is that you have a much wider variety of languages, although Azure Data Studio has a SQL Server kernel, which other platforms currently do not have.

Comments closed

Lessons from using Notebooks

Published 2021-04-14 by Kevin Feasel

Glenn Berry takes us through some of the past (and sometimes present) challenges of running notebooks in Azure Data Studio:

I have to admit that I do not use Jupyter notebooks or Azure Data Studio (ADS) everyday. Last August, I made separate Jupyter notebook versions of my SQL Server Diagnostic Information Queries. There was a separate version for SQL Server 2012 through SQL Server 2019, along with one for Azure SQL Database. This was after a number of requests from people in the community.

Creating these notebooks was a pretty decent amount of work. Luckily, this was right around the time that Azure Data Studio was making it much easier to edit and format markdown for the text blocks. Since then, Azure Data Studio is even easier to use for editing and formatting. Even more fortuitous was the fact that Julie Koesmarno (@MsSQLGirl) volunteered to greatly improve my formatting!

Unfortunately, there has not been as much interest in my Jupyter notebooks as I hoped for. There are probably a number of reasons for this.

Read on for Glenn’s notes.

Comments closed