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Author: Kevin Feasel

Digging Into The SQL Compute Context With R Services

Published 2018-05-21 by Kevin Feasel

Niels Berglund dives into how the SQL Compute Context works with R Services:

In the code above we use the RxInSqlServer() function to indicate we want to execute in a SQL context. The connectionString property defines where we execute, and the numTasks property sets the number of tasks (processes) to run for each computation, in Code Snippet 4 it is set to 1 which from a processing perspective should match what we do in Code Snippet 3. Before we execute the code in Code Snippet 4 we do what we did before we ran the code in Code Snippet 3:

  • Run Process Explorer as admin.
  • Navigate to the devenv.exe process in Process Explorer.
  • In addition, also look at the Launchpad.exe process in Process Explorer.

When we execute we see that the BxlServer.exe processes under the Microsoft.R.Host.exe processes are idling, but when we look at the Launchpad.exe process we see this:

This is a bit deep but interesting reading.

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Creating Choropleths With ggcounty

Published 2018-05-21 by Kevin Feasel

Sebastian Sauer has a quick example of using ggcounty to plot data on a map of US counties:

This posts shows how easy it can be to build an visually pleasing plot. We will use hrbrmster’s ggcounty, which is an R package at this Github repo. Graphics engine is as mostly in my plots, Hadley Wickhams ggplot. All build on R. Standing on shoulders…

Disclaimer: This example heavily draws on hrbrmster example on this page. All credit is due to Rudy, and those on whose work he built up on.

In just a few lines of code, you can have a pretty nice map.

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Getting Month Names Given Numbers In DAX

Published 2018-05-21 by Kevin Feasel

Philip Seamark shows how to convert month numbers into names in Power BI:

The most common solution I see offered is along the lines of a SWITCH statement that lists 12 conditions (one for each month).   This works, but can also be done using existing functions.

While DAX lacks a dedicated function to convert a number to a text version, such as DATENAME in T-SQL, we can get there in two functions using DATEVALUE wrapped in a FORMAT.

To demonstrate, I will create a simple table with 13 values (1 through 13) using the following calculated table.

This creates a single column table with 13 rows.

Read on for the rest of the story.

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Overlaying Visuals In Power BI

Published 2018-05-21 by Kevin Feasel

Annie Xu gives us two methods for being able to jump between two visuals in the same space:

Disconnected Table method:

This method is more towards PowerBI modelers. Basically, the idea is to have a Field in a independent table (no relationship to other tables) as Slicer with your measure choice and then create a measure using SELECTEDVALUE function to have the measure dynamically switch referring measures based on the choice made on the slicer.

Click through for both methods.

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JSON Data In SSIS

Published 2018-05-21 by Kevin Feasel

Stacia Varga shows a few methods for handling JSON data in SQL Server Integration Services:

And then I had to write about it in my book Introducing Microsoft SQL Server 2016 (which is free to download) when JSON support was added to SQL Server 2016. But I still didn’t have clients using JSON. It was interesting to me that I could use SQL Server to work with JSON data, but it was still theoretical to me rather than practical.

Therefore, I never thought much about how I would handle it in SQL Server Integration Services (SSIS). I just didn’t have a reason.

Until now. This seems to be the year that I am bumping into JSON left and right. It’s everywhere!

Read on for those methods as well as Stacia’s recommendation.

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Exporting Table Details With Powershell

Published 2018-05-21 by Kevin Feasel

Andy Levy helps an end user understand a database schema:

This week I had a user come to me asking about how fields were defined on a few tables he was using in writing some reports. Long story short, he’s been tasked with writing some new reports and updating existing ones, but he doesn’t have visibility to the database itself so he’s left with the “ok, let’s try this” approach and then reading error messages to debug when things go sideways. Very tedious.

I asked him for a list of the tables he was most interested in, and while he worked on that I set to work on (of course) a quick & dirty PowerShell script to collect the data he needed – field names, types, and whether they’re nullable.

Ideally these analysts would have data model documentation, but it’s not an ideal world.

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Choose Your Hadoop File Format

Published 2018-05-18 by Kevin Feasel

Alex Woodie explains three of the most common Hadoop file formats:

You have many choices when it comes to storing and processing data on Hadoop, which can be both a blessing and a curse. The data may arrive in your Hadoop cluster in a human readable format like JSON or XML, or as a CSV file, but that doesn’t mean that’s the best way to actually store data.

In fact, storing data in Hadoop using those raw formats is terribly inefficient. Plus, those file formats cannot be stored in a parallel manner. Since you’re using Hadoop in the first place, it’s likely that storage efficiency and parallelism are high on the list of priorities, which means you need something else.

Luckily for you, the big data community has basically settled on three optimized file formats for use in Hadoop clusters: Optimized Row Columnar (ORC), Avro, and Parquet. While these file formats share some similarities, each of them are unique and bring their own relative advantages and disadvantages.

Read the whole thing.  I’m partial to ORC and Avro but won’t blink if someone recommends Parquet.

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Using The Map Function In R

Published 2018-05-18 by Kevin Feasel

Nicolas Attalides on using purrr:

The best place to start when exploring the purrr package is the map function. The reader will notice that these functions are utilised in a very similar way to the apply family of functions. The subtle difference is that the purrr functions are consistent and the user can be assured of the output – as opposed to some cases when using for example sapply as I demonstrate later on.

My considered belief is, Always Be Purrring.  H/T R-bloggers

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Storing An Encrypted Password In The Solr Configuration File

Published 2018-05-18 by Kevin Feasel

Jon Morisi shows us how to store an encrypted password in Solr’s configuration file, rather than storing the password in plaintext:

The config file has a lot of options, in short this is where you configure a database connection string and reference your jdbc jar file. Full details are here.  By default any of the examples that come with the Solr distribution use a plain text username and password.  This can be potentially viewed from the front end:
http://hostname:8983/solr/ > Select Collection from the drop-down > Click data Import > expand configuration
Obviously we do not want to store our username and password in plain text.  The config file includes an option to encrypt the password and then store the key in a separate file.

Storing passwords in plaintext is a classic mistake that I see far too often.  And then when someone checks in that config file to a public GitHub repo…

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T-SQL Join Delete

Published 2018-05-18 by Kevin Feasel

Steve Stedman walks us through a bit of T-SQL proprietary syntax:

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DELETE t2
FROM [dbo].[Table1] t1
INNER JOIN [dbo].[Table2] t2 on t1.favColor = t2.id;

Names have been changed to protect the innocent.

In the above delete statement which table will have rows deleted from it?

A: Table1

B: Table2

C: Both Table1 and Table2

D: Neither Table1 and Table2

Got it in one.  I like having this syntax available to me when I need it, even though it’s not ANSI standard.

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