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Author: Kevin Feasel

Latches to Know

Published 2021-09-20 by Kevin Feasel

Paul Randal wraps up a series on latches with a few miscellaneous entries:

When either a heap or an index is being accessed, internally there’s an object called a HeapDataSetSession or IndexDataSetSession, respectively. When a parallel scan is being performed, the threads doing the actual work of the scan each have a “child” dataset (another instance of the two objects I just described), and the main dataset, which is really controlling the scan, is called the “parent.”

When one of the scan worker threads has exhausted the set of rows it’s supposed to scan, it needs to get a new range by accessing the parent dataset, which means acquiring the ACCESS_METHODS_DATASET_PARENT latch in exclusive mode. While this can seem like a bottleneck, it’s not really, and there’s nothing you can do to stop the threads performing a parallel scan from occasionally showing a LATCH_EX wait for this latch.

Click through to read the whole thing.

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Remember CPU Time when Optimizing Power BI Premium Reports

Published 2021-09-20 by Kevin Feasel

Chris Webb has a public service announcement:

When you tune a Power BI report or dataset refresh your first job is to make it run faster – users hate slow reports and late data. However, if you are using Power BI Premium you also need to think about reducing the amount of CPU used by a query or refresh as well, and in this post I’ll explain why.

Click through for that explanation.

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Concatenating in SQL Server

Published 2021-09-20 by Kevin Feasel

Lee Markup takes us through a pair of very useful functions in SQL Server:

SQL Server concatenation methods have been enhanced in modern versions of SQL Server. SQL Server 2012 introduced the CONCAT() function. In SQL Server 2017 we get CONCAT_WS().

A common usage of concatenation, or joining column values together in a string, is combining a FirstName and LastName column into a FullName column.  Another common usage might be for creating an address column that pulls together building number, street, city and zip code.

Read on to learn more. CONCAT() and CONCAT_WS() are also extremely helpful for change detection in ETL processes. For example, you might have a queue table to process and only want to update records in which relevant source fields changed, ignoring the ones which don’t exist in your destination. A combination of HASHBYTES() and CONCAT_WS() will do the trick quite nicely.

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Software Development Estimation is Hard

Published 2021-09-20 by Kevin Feasel

Andy Leonard makes a point:

I recently blogged about punching developers in the brain when a software deliverable deadline is slipping. The title of the post is The Question Unasked. In this post, I would like to address software development estimation.

In the past, I have stated “Either all software developers are pathological liars or software development is inherently inestimable.”

Read on for Andy’s take. For mine, the overly short version is that incentives are set up for software estimation to fail due to perverse incentives and a lack of requirements. Ask the question, “How long will it take to build a skyscraper?” and you might get some answer, but it certainly won’t be the answer to the pertinent question, “How long will it take to build this skyscraper?” That’s because we haven’t talked at all about location, building plans, blueprints, regulatory requirements, financing, or any of the hundreds of other things which organizations talk about and do before they start slapping mortar on bricks. With software development, we’re expected to wing it and solve all of those sorts of problems along the way. Making it even better, more often than not, the skyscraper “pivots” to being a suspension bridge.

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The Reason for Tail Log Backups

Published 2021-09-20 by Kevin Feasel

Chad Callihan explains why we need tail log backups:

When you are migrating a database from one server to another, how can you be sure to backup all transactions? Sure, you can notify the client and let them know “there will be a short outage at 8AM so please stay out of the application at that time.” Can you really trust that? Of course not. Let’s demonstrate the steps needed to include all transactions with the tail-log backup.

Protip: if you build your application such that nobody wants to use it, you can migrate the database much more easily. Assuming you don’t want to follow that outstanding advice, Chad has you covered.

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Analog and Digital Clocks in R

Published 2021-09-17 by Kevin Feasel

Tomaz Kastrun reminds me of xclock:

It is all about measuring time using useless clocks. Script takes a system time and displays any given clock in a rather “static” way. You can choose between analog, small digital and big digital clock. And when playing with the time, you can also learn something new.

Click through to see how to make an analog clock plot in R, and then try it again with a digital clock.

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Where Kafka Connect Fits

Published 2021-09-17 by Kevin Feasel

Shivani Sarthi explains the value of Kafka Connect:

Kafka connect is not just a free, open source component of Apache Kafka. But it also works as a centralised data hub for simple data integration between databases, key-value stores etc. The fundamental components include-

– Connectors

– Tasks

– Workers

– Converters

– Transforms

– Dead letter Queue

Moreover it is a framework to stream data in and out of Apache Kafka. In addition, the confluent platform comes with many built-in connectors,used for streaming data to and from different data sources.

Click through for information on each component.

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Slot Machine Company Data Breach

Published 2021-09-17 by Kevin Feasel

Jonathan Greig reports on a data breach:

Nevada Restaurant Services (NRS), the owner of popular slot machine parlor chain Dotty’s, has disclosed a data breach that exposed a significant amount of personal and financial information. 

In a statement, the company confirmed that “certain customers” were affected by the breach and explained that the information includes Social Security numbers, driver’s license numbers or state ID numbers, passport numbers, financial account and routing numbers, health insurance information, treatment information, biometric data, medical records, taxpayer identification numbers and credit card numbers and expiration dates.

I don’t normally link to data breaches too often because if I did, this site would be renamed to Curated Data Breaches given how frequently they occur. But what I want to know is, why in the world does a slot machine company have passport numbers, health insurance information, and medical records? What are they doing with that information? Slot machines are pretty simple: put quarter in, watch the screen light up and speakers make a bunch of happy noises, repeat until you run out of quarters. Unless there’s some sort of business arrangement where they put slot machines in the Nevada hospitals…

Also, the fact that credit card numbers and expiration dates were lost makes me wonder if they were actually PCI compliant.

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Creating a Distributed Availability Group in Azure via Terraform

Published 2021-09-17 by Kevin Feasel

Sandeep Arora has some scripts for us:

To create a distributed availability group, you need two availability groups (AG) each with its own listener, which you then combine.In this case, one availability group is on-premises and the other needs to be created in Microsoft Azure. This example doesn’t cover all of the details like creating an extended network setup between on-premises network and Azure or joining Azure active directory domain services to and on-premises forest; instead, it highlights the key requirements for setting up the availability group in Azure and then configuring the distributed AG between the on-premises availability group (represented as AOAG-1) and the Azure availability group (represented as AOAG-2).

Click through for the preparations you need in place and a set of scripts to do the work.

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