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Author: Kevin Feasel

Using sp_prepare with Plan Guides

Published 2021-01-13 by Kevin Feasel

Aaron Bertrand tries something different:

There are features many of us shy away from, like cursors, triggers, and dynamic SQL. There is no question they each have their use cases, but when we see a trigger with a cursor inside dynamic SQL, it can make us cringe (triple whammy).

Plan guides and sp_prepare are in a similar boat: if you saw me using one of them, you’d raise an eyebrow; if you saw me using them together, you’d probably check my temperature. But, as with cursors, triggers, and dynamic SQL, they have their use cases. And I recently came across a scenario where using them together was beneficial.

Read on to see the method to this madness.

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Security Update for SQL Server

Published 2021-01-13 by Kevin Feasel

Randolph West takes a look at a patch:

Microsoft announced updates today for all supported versions of SQL Server, for a privilege escalation vulnerability that leverages Extended Events. For security reasons no further details have been provided, but you can expect more information in the near future, now that this update is public.

Be sure to grab the latest update for your version of SQL Server.

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Little Things in Azure Data Factory

Published 2021-01-13 by Kevin Feasel

Rayis Imayev has some kind words about small niceties in Azure Data Factory:

Recently Microsoft team conducted a brief year-end survey about a “one thing” that Azure Data Factory (ADF) “made your day in 2020” – https://twitter.com/weehyong/status/1343709921104183296. There were different responses from the global parameters support to the limit increase of ADF instances per subscription.

I personally like the little things that are not easily detected on a surface, but with a deeper immersion into a data pipeline development, your level of gratefulness increases even more.

Click through for a few examples.

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Improving a Graph

Published 2021-01-12 by Kevin Feasel

Elizabeth Ricks has started a series on improving a particular visual:

I empathize with the plight of this anonymous creator. In previous roles, I frequently created visuals that looked like this, and was left frustrated when requests came back for “more data.” I slowly came to realize that I was assigning my audience the tedious task of figuring out for themselves what the takeaways were. My visuals should have been highlighting the interesting things to those seeing them for the first time. The five questions we’ll be discussing in this series will help us to do just that.

The first question in the series is, “What elements can I eliminate?” I think that’s a really good idea—with data visualization, less is more.

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Hyperparameter Tuning as Technical Debt

Published 2021-01-12 by Kevin Feasel

John Mount has an interesting take on hyperparameter tuning:

The hyper dance is the venial trick of pushing user facing technical debt and flaws as user controllable features. These controls are usually named “hyper parameters” and they are parameters or arguments that control the behavior of an algorithm. Users think “hyper parameters” must be even better than “regular parameters”, just like “hyper drive” is better than “sub-light drive.” However the etymology of the name isn’t from science fiction, it is just the need in statistical contexts to have a name for controls other than parameter, as parameter is often used to name the fit coefficients of a model (i.e. to name an output, not an input!).

In addition to this, I’d be concerned that heavy hyperparameter tuning could lead to a garden of forking paths problem where we end up accidentally doing the equivalent of p-hacking: modifying hyperparameters until we come up with the “right” answer.

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Archival on Delete in SQL Server

Published 2021-01-12 by Kevin Feasel

Erik Darling shows off a pattern:

Well, friends, I have good news for you. This is an easy one to implement.

Let’s say that in Stack Overflow land, when a user deletes their account we also delete all their votes. That’s not how it works, but it’s how I’m going to show you how to condense what can normally be a difficult process to isolate into a single operation.

The one gripe I have with this post is that my annoyingly loud keyboard is buckling spring, not Cherry MX Blue, thank-you-very-much.

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Azure Data Factory and Source Control

Published 2021-01-12 by Kevin Feasel

Ahmad Yaseen shows how you can save Azure Data Factory pipelines in source control:

To overcome these limitations, Azure Data Factory provides us with the ability to integrate with a GIT repository, such as Azure DevOps or GitHub repository, that helps in tracking and versioning the pipelines changes, and incrementally save the pipeline changes during the development stage, without the need to validate the incomplete pipeline, preventing these changes from being lost in case of any crash or failure. In this case, you will be able to test the pipeline, revert any change that is detected as a bug, and publish the pipeline to the Data Factory when everything is developed and validated successfully.

Click through for the setup instructions.

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Query Store and Cross-Database Queries

Published 2021-01-12 by Kevin Feasel

Matthew McGiffen does some research:

When I was writing the script shared in my last post Identify the (Top 20) most expensive queries across your SQL Server using Query Store a question crossed my mind:

Query Store is a configuration that is enabled per database, and the plans and stats for queries executed in that database are stored in the database itself. So what does query store do when a query spans more than one database?

Read on for the answer.

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Smoothing and its Inherent Risks

Published 2021-01-11 by Kevin Feasel

John Mount would like you to take care when using smoothers:

Here is a quick data-scientist / data-analyst question: what is the overall trend or shape in the following noisy data? For our specific example: How do we relate value as a noisy function (or relation) of m? This example arose in producing our tutorial “The Nature of Overfitting”.

One would think this would be safe and easy to asses in R using ggplot2::geom_smooth(), but now we are not so sure.

Here’s a quick summary of my general philosophy: the data are more interesting than a smoothed line. I’m okay putting in a smoothed line to help a reader make sense of a trend, but I wouldn’t want to have a plot with just the smoothed line. Read the whole thing from John to get well beyond my rule of thumb.

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