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Category: Misc Languages

How .NET Code Talks to Spark

Ed Elliott has a great diagram showing how user-written .NET code communicates with Spark over the Java VM:

4. Spark-dotnet Java driver listens on tcp port
The spark-dotnet Java driver listens on a TCP socket. This socket is used to communicate between the Java VM and the dotnet code, the dotnet code doesn’t run in the Java VM but is in a separate process communitcating with the Java VM via that TCP postrt. The year is 2019, we serialize and deserialize data all the time and don’t even know it, hell notepad probably even does it.

It’s serialization & deserialization as well as TCP sockets all the way down.

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Spark and dotnet in a Single Container

Ed Elliott shows how you can combine Spark and .NET Core in a single Docker container:

This is quite new syntax in docker and you need at least docker 17.05 (client and daemon), after the images “FROM blah” you can specify a name “core” in this case, then later you can copy from the first image to the second using “–from=” on the “COPY” command.

In this dockerfile I have added Spark 2.4.3 and the default environment variables we need to get spark running, if you grab this dockerfile and run “docker build -t dotnet-spark .” you should get an images you can then run which includes the dependencies for dotnet as well as spark.

Ed includes all of the scripts needed to test this out, too.

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Scala 2.13 Changes

Anmol Sarna takes us through what’s new in Scala 2.13:

Last, but not the least, the team has invested heavily in compiler speedups during the 2.13 cycle which resulted in some major changes with respect to the compiler.

Compiler performance in 2.13 is 5-10% better compared to 2.12, thanks mainly to the new collections.

There are a lot of changes in this version. I wonder how long before Spark supports it fully.

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CQL: Category Theory-Based Querying Language

John Cook looks at a querying language based on category theory:

My interest in category theory waxes and wanes, and just as it was was at its thinnest crescent phase I ran across CQL, categorical query language. I haven’t had time to look very far into it, but it seems promising. The site’s modest prose relative to the revolutionary rhetoric of some category enthusiasts makes me have more confidence that the authors may be on to something useful.

I’m going through some lectures on category theory now and am in a big functional programming phase, so this is interesting but I won’t be giving up SQL anytime soon for it.

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Unicode Escaping Across Various Languages

Solomon Rutzky shows how to perform Unicode character escaping in a dozen places:

The purpose of this post is to correct the overall lack of examples. Everything shown below are actual working examples of creating both a Unicode-only BMP character (meaning a non-Supplementary Character that would require Unicode) and a Supplementary Character. Most examples include a link to an online demo, either on db<>fiddle (for database demos) or IDE One (for non-database demos), both very cool and handy sites.

This includes T-SQL and MySQL as well as .NET languages, PHP, JavaScript, and even Excel. It’s a handy reference page.

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Case-Insensitive Searches in Snowflake

Koen Verbeeck shows how you can perform case-insensitive searches in Snowflake DB:

I’m doing a little series on some of the nice features/capabilities in Snowflake (the cloud data warehouse). In each part, I’ll highlight something that I think it’s interesting enough to share. It might be some SQL function that I’d really like to be in SQL Server, it might be something else.

Today I have a small blog post about a neat little function I discovered last week – with thanks to my German colleague, who wants to remain anonymous. The function is called ILIKE and it is syntactic sugar for the combination of UPPER and LIKE.

I’m personally not a fan of case-sensitive collations for data; it’s hard for me to understand the meaningful differences between “dog,” “Dog,” and “DOG.”

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Using the ML.NET Model Builder

I have a post looking at the ML.NET Model Builder:

You have four options from which to choose: two-class classification, multi-class classification, regression, or Choose Your Own Adventure. Today, we’re going to create a two-class classification model. Incidentally, they’re not kidding about things changing in preview—last time I looked at this, they didn’t have multi-class classifiers available.

Once you select Sentiment Analysis (that is, two-class classification of text), you can figure out how to feed data to this trainer.

I think this is fine for developers who are looking to add a machine learning component as a small part of a bigger product. I don’t think it will beat a trained human using R or Python, but it’s an interesting avenue.

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Creating Models with ML.NET

I have a series on ML.NET; in this post, I look at building a model:

Okay, now that I have classes, I need to put in that lambda. I guess the lambda could change to qb => qb.Quarterback == "Josh Allen" ? "Josh Allen" : "Nate Barkerson" and that’d work except for one itsy-bitsy thing: if I do it the easy way, I can’t actually save and reload my model. Which makes it worthless for pretty much any real-world scenario.

So no easy lambda-based solution for us. Instead, we need a delegate. 

The experience so far has been a bit frustrating compared to doing similar work in R, but they’re actively working on the library, so I’m hopeful that there will be improvements. In the meantime, I’ve landed on the idea of doing all data cleanup work outside of ML.NET and just use the simplest transformations.

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Using Java in SQL Server 2019

Niels Berglund has an update on writing Java code in SQL Server 2019:

In CTP 2.5 and onwards when you write Java code for SQL Server you implement your code using the Microsoft Extensibility SDK for Java, (SDK). The SDK acts sort of like an interface as it exposes abstract classes that your code need to extend/target, (more about that later).

The SDK comes in the form of a .jar file, and you download the SDK from here.

Niels dives deep into the topic, so set aside a bit of time to read through this one.

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