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Category: Misc Languages

Deconstructing Running Totals with M

Published 2020-03-31 by Kevin Feasel

Cedric Charlier shows how to turn a running total into a periodic series of events with M:

When dealing with time series, you should always check if your time series are event-based or cumulative. For a time series with a step of one day, an event-based time series will contain the count of events for a given day. A cumulative time series will contain the sum of the event of that day and of all the previous days! In this blog post I’ll explain how to transform a cumulative time series into an event-based.

Click through for the code. You can do this in T-SQL as well by subtracting the value from its LAG()-ged value.

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Parameterization and Enumerable.Contains() with EF Core 3

Published 2020-03-31 by Kevin Feasel

Erik Ejlskov Jensen explains how we can prevent Entity Framework Core 3 from polluting the plan cache if we use Enumerable.Contains():

One of the many advantages of using a tool like Entity Framework Core is, that you are sure that the framework will generate properly parameterized SQL for you. This helps avoid SQL injection issues and avoids plan cache pollution. Unfortunately, EF Core currently falls short on that promise, when translating queries, where you supply a list of values to be matched against a column – Enumerable.Contains method – this is translated to a SQL Server IN operator

Click through for a setup of the problem as well as the solution.

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Coding Tips for a Younger Self

Published 2020-03-24 by Kevin Feasel

Parvinder Nijjar has some good tips for less-experienced developers:

Always break a big problem into a series of small problems. Sometimes a big problem can feel daunting and be more difficult than it seems. Break the problem down into smaller blocks and then solve each block one at a time. It’s okay to skip a block and return to a previous block as it may give you clues to fixing the skipped block. In all honesty whilst coding the parts you can do a piece of divine inspiration will enable you to problem you couldn’t solve or you will enough code to show one of your more capable colleagues that you had tried to fix the issue and now this rubbish was there problem to fix.

I am basically at the point of self-parody in my love of functional programming languages, but this is one of those things FP really reinforces: bottom-up development and chaining together lots of little pieces to create big pieces. But there is good advice in here no matter what language you use.

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Microsoft to Acquire npm via GitHub

Published 2020-03-17 by Kevin Feasel

Joab Jackson breaks the news:

Code repository service GitHub is in the process of acquiring the preeminent software registry for Node.js and JavaScript modules, npm, the two companies announced Monday.

GitHub plans to invest in npm’s infrastructure, with the hopes of bringing some much-needed modernization to the platform, GitHub CEO Nat Friedman promised in a blog post. It also may help free the rapidly-growing registry from the considerable financial and personnel turmoil that it has been inflicted with over the past few years.

I for one welcome leftpad by Microsoft.

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Managing Azure SQL Database with Golang

Published 2020-03-06 by Kevin Feasel

Silvano Coriani shows us that it’s possible to manage Azure SQL Databases with Go:

Goal for this post is to introduce how to start interacting with Azure SQL through Go (https://golang.org/), an open source programming language gaining lots of traction in developers’ community thanks to its simplicity and efficiency in scenarios like microservices and server apps (did I mention that Kubernetes itself is written in Go?).  

Azure SQL provides full support for Go developers on both control plane (deploy, manage and configure Azure SQL servers and databases) and data plane activities (connect, execute commands and queries against Azure SQL instances) through Azure SDK for Go and Microsoft SQL Server Driver for Go.

A companion code sample for this article, written using VS Code, can be found here.

To me, this is like the articles written back in 2007-2008 about how to manage SQL Server with Python. It’s cool and I hope it helps some people learn the language or find another good use for it, but I’m not sure it moves the needle.

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High-Throughput REST APIs with Dapper and Azure SQL DB

Published 2020-02-24 by Kevin Feasel

Davide Mauri builds out an example of a WebAPI project using Dapper to query Azure SQL Database:

I was able to execute 1100 Requests Per Seconds with a median response time of 20msec. If you can accept a bit higher latency, you can also reach 1500 RPS but the median response time becomes 40msec and the 95 percentile is set at 95msec. Database usage never goes above 20% in such cases…and in fact the bottleneck is the Web App (better, the Web App Plan) and more specifically the CPU. Time to scale up or out the Web App Plan.

By scaling up and out a bit, I was able to reach almost 10.000 request per second with just an HS_Gen5_4. Quite impressive.

I like Dapper as a micro-ORM. Products like it and FSharp.Data.SqlClient are good examples of how you can remove a lot of middleware goop without taking on the performance burdens of Entity Framework and Hibernate.

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Executing Azure Data Factory Pipelines with Azure Functions

Published 2020-02-21 by Kevin Feasel

Paul Andrew wants to execute an Azure Data Factory pipeline via an Azure Function call:

For the function itself, hopefully this is fairly intuitive once you’ve created your DataFactoryManagementClient and authenticated.

The only thing to be careful of is not using the CreateOrUpdateWithHttpMessagesAsync method by mistake. Make sure its Create Run. Sounds really obvious, but when you get code drunk names blur together and the very different method overloads will have you confused for hours!…. According to a friend 🙂

Read the whole thing.

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Creating a Delimited List in .NET

Published 2020-02-21 by Kevin Feasel

Bill Fellows wants you to use a built-in library method:

There are various ways to concatenate values together. A common approach I see is that people will add a delimiter and then the value and loop until they finish. Then they take away the first delimiter. Generally, that’s easier coding, prepending a delimiter, than to append the delimiter and not do it for the final element of a list. Or add it and then remove the final delimiter from the resulting string.

Gentle reader, there is a better way. And has been for quite some time but if you weren’t looking for it, you might not know it exists. 

You do get bonus points if you knew this existed.

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Installing .NET Notebooks for Powershell

Published 2020-02-18 by Kevin Feasel

Max Trinidad shows us how to install .NET Interactive on Linux:

In Windows, just takes a few steps to set it up. For Linux, it takes a few extra steps but still is quick enough to get you started.

For Windows, follow the instructions found at the .NET Interactive page in Github.

For Linux, for Ubuntu 18.04, follow the blog post “Ubuntu 18.04 Package Manager – Install .NET Core“.

Basically, in either operating systems, you install:

– Install the .NET Core SDK
– Install the ASP.NET Core runtime
– Install the .NET Core runtime

Click through for the step-by-step instructions. Once you have it done, you get not only Powershell but also F# and C#.

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Fun with Binding Redirects in .NET

Published 2020-02-12 by Kevin Feasel

Nick Craver has some advice if you see binding redirect problems:

You’re probably here because of an error like this:

Could not load file or assembly ‘System.<…>, Version=4.x.x.x, Culture=neutral, PublicKeyToken=<…>’ or one of its dependencies. The system cannot find the file specified.

And you likely saw a build warning like this:

warning MSB3277: Found conflicts between different versions of “System.<…>” that could not be resolved.

Whelp, you’re not alone. We’re thinking about starting a survivors group. 

Read on for Nick’s advice here. This is particularly tricky with F# and especially when you use type providers, as that can easily lead to a version mismatch in FSharp.Core. I’ve spent way too much time tracking those down.

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