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Day: November 2, 2021

Event-Driven Programming

Gigi Sayfan explains the idea of event-driven programming:

Event-driven programming is a great approach for building complex systems. It embodies the divide-and-conquer principle while allowing you to continue using other approaches like synchronous calls.

When discussing event-based systems, several different terms often refer to the same concept. For simplicity, we’ll primarily use the terms listed below in bold:

Event, message, and notification

Producer, publisher, sender, and event source

Consumer, receiver, subscriber, handler, and event sink

Message queue and event queue

I really like the ideas behind event-driven programming. It’s most commonly useful when working with cloud services, but also in solving some difficult T-SQL problems.

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GROUP BY and Functional Dependencies

Lukas Eder illuminates us:

The SQL standard knows an interesting feature where you can project any functional dependencies of a primary (or unique) key that is listed in the GROUP BY clause without having to add that functional dependency to the GROUP BY clause explicitly.

I was unaware that this functionality existed (in some database platforms), and I’m not positive that I like it.

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Paul Randal does some explaining:

I had an email question over the weekend where someone noticed that while executing a scan of a heap using NOLOCK, there was a BULK_OPERATION lock held on the heap for the duration of the scan. The question was why is the BULK_OPERATION lock needed, as surely there’s no way for the NOLOCK scan to read a problematic page?

Well, the answer is that the extra lock is needed *precisely* because the NOLOCK scan *can* read a problematic page if there’s a bulk operation happening on the heap at the same time.

And don’t call me Shirley.

Click through for a demonstration of this answer.

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Restrictions for Parallel Insertion

Erik Darling summarizes the main man:

I’d like to start this post off by thanking my co-blogger Joe Obbish for being lazy and not blogging about this when he first ran into it three years ago.

Now that we’re through with pleasantries, let’s talk turkey.

Over in this post, by Arvind Shyamsundar, which I’m sure Microsoft doesn’t consider official documentation since it lacks a GUID in the URL, there’s a list of… things about parallel inserts.

Read on for the summary of limitations.

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Secure FTP in Powershell

Chad Baldwin needs to send a file:

Over the years I’ve written dozens of these, one thing that often hangs me up are the “copy to SFTP” and “copy from SFTP” steps. usually what happens is I build two scripts…an “export script”, which has a manual step of “open FileZilla and upload file”, and then an Import script with another manual step to download the file.

After some Google searching to see how to handle SFTP in PowerShell, I ran into this StackOverflow answer (the creator of WinSCP) which introduced me to some cool new alternatives for dealing with FTP, FTPS, SFTP, SCP, etc using PowerShell.

Click through to see one way to do it, as well as some additional recommendations from Viewers Like You.

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