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Curated SQL Posts

Notes on Temporal Tables

Published 2021-07-07 by Kevin Feasel

Hugo Kornelis wraps up a discussion of temporal tables with miscellany:

Of course, it will be a quite common requirement to query products and their suppliers. When querying the present, you can just access the Suppliers and Products table without the “FOR SYSTEM_TIME” keyword, and the execution plan will unsurprisingly show that a regular join of the two “current” tables is used, with no reference to the history table. Nothing special. We already saw in the earlier parts that querying the present simply ignores the history table; joining does not make that different.

But what if, for instance, we want to show all data as it was valid on June 3 at noon? Well, that is also simple. We already know that we can use FOR SYSTEM_TIME AS OF” to get the rows from a single temporal table as they were at a specific time. We can use that syntax for both tables, to get the data we need:

Read on as Hugo dives into some messy problems. Temporal table queries can expand out in complexity very quickly, as this post shows.

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Introducing the Display-Object Cmdlet

Published 2021-07-07 by Kevin Feasel

Phil Factor has a bit of Powershell for us:

How do you list all the objects and values within a PowerShell object, investigate an object or explore its structure? There must be a simple way. I used to use ConvertTo-JSON. This is fine up to a point but what if you just wish to search for strings or look for objects with a cartain name or value? What if you need their path so you can reference them? It isn’t plain-sailing. In the ISE, the intellisense will help you a lot but I want more and I want to do it in script rather than the IDE

Read on to check it out and get a copy of the cmdlet.

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Migrating Historical Data from Azure Analysis Services to Power BI Premium Per User

Published 2021-07-07 by Kevin Feasel

Gilbert Quevauvilliers continues a series on moving to Power BI Premium Per User:

In this blog post I am looking at how to load or reload historical data in AAS and PPU and compare the differences.

It should already be noted that I am only going to compare tables where I have partitions created and enabled. The reason being for dimension tables it is typically quick and easy to reload the data by re-processing the data for the table.

Read on for the details.

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Required Permissions for Forcing Query Store Plans

Published 2021-07-07 by Kevin Feasel

Grant Fritchey reviews minimum requirements:

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.

Click through for the disappointing answer.

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Against sp_hexadecimal and sp_help_revlogin

Published 2021-07-07 by Kevin Feasel

Andy Mallon says it’s time to give up a couple of procedures:

We recently ran into some performance problems with our login sync, which is based on sp_hexadecimal and sp_help_revlogin, the documented & recommended approach by Microsoft.

I’ve been installing & using these two procedures since I started working with SQL Server, back at the turn of the century. In the nearly two decades since, I’ve blindly installed & used these procedures, first on SQL Server 2000, and then on every version since… just because that’s the way I’ve always done it. But our recent performance problems made me rethink that, and dive in to take a look at the two procedures to see if I could do better, which made me realize, OHBOY! WE CAN DO BETTER!!

Read on to understand how.

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Goodbye, SQL Server on Windows Containers

Published 2021-07-06 by Kevin Feasel

Amit Khandelwal shuts the doors:

As you may be aware, the SQL Server on Windows Containers Beta program began in 2017. It has remained in Beta mode meant for only test and development environment until now. Due to the existing ecosystem challenges and usage patterns we have decided to suspend the SQL Server on Windows Containers beta program for foreseeable future. Should the circumstances change, we will revisit the decision at appropriate time and make relevant announcement.

I never heard of many people using Widows containers, but with the differences in available products and features between Windows and Linux versions of SQL Server, I can see why some people would want to use them.

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Handling Tombstones in Cassandra

Published 2021-07-06 by Kevin Feasel

Payal Kumari takes us through tombstone management in Apache Cassandra:

Got too many tombstones? This blog post will talk about how to deal with tombstones once you already have them. For more information about tombstones, check out this post: Examining the Lifecycle of Tombstones in Apache Cassandra.

Click through for several techniques for handling tombstoned records in Cassandra. In SQL Server, with columnstore indexes, the prevention advice is similar (avoid deletion or updating of data) but the treatment options are quite different.

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The Importance of SQL for Data-Related Jobs

Published 2021-07-06 by Kevin Feasel

Camila Henrique explains the importance of knowing SQL:

I wanted to talk about this because I see a lot of doubts and lack of direction from people who are either beginning now in IT land or thinking about switching careers. The short answer to “do I need to know SQL for a data job?” , is yes. In the next few paragraphs I explain why I think so.

It’s easy to get caught up in all the fancy programming languages and methodologies for projects that sometimes the basics… are just not there. I believe having a good foundation opens paths to other doors that you could not see before. And I’m certain that SQL is one hell of a foundation to have in the data land.

This is also a good time to slip in a reminder of Feasel’s Law.

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Is sysname Case-Insensitive?

Published 2021-07-06 by Kevin Feasel

Solomon Rutzky tries Betteridge’s Law of Headlines:

Over time I’ve used a variety of SQL Server versions with a variety of instance-level collations. This has lead me to conclude that sysname had to be all lower-case in some earlier versions if the instance-level collation was either binary or case-sensitive. However, it was not clear exactly which versions and what scenarios truly affected the behavior of sysname name resolution, so I played it safe and continued to always specify that particular data type in all lower-case, even leaving comments in scripts that it must remain as all lower-case (just in case someone goes through and tries to make it upper-case to be consistent with the other data types).

But then, while researching another topic, I recently found the following in some old documentation ( Breaking Changes to Database Engine Features in SQL Server 2005 ):

Read on for the results of Solomon’s archaeological expedition.

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Power BI Report Iconography

Published 2021-07-06 by Kevin Feasel

Joe Billingham brings in the Unicode characters:

There are 143,859 Unicode characters available, everything from emojis, symbols, shapes and braille patterns to dice and playing cards. Whether you want to offer further insight into your data, enhance the user experience or simply create something sublimely ridiculous, with so many icons at your fingertips, the possibilities are only limited by your imagination.

Click through to see how you can include specific Unicode characters to create a visual link in the mind of your viewer to your data.

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