Press "Enter" to skip to content

Author: Kevin Feasel

Who Monitors The Monitors?

Published 2016-10-12 by Kevin Feasel

Dave Mason discusses monitors and what happens when they fail:

I was reminded of this recently in my little SQL Server world. I have a number of garden variety alerts set up, plus some other more custom monitoring stuff, which is mostly tied to DDL triggers and event notifications. The one thing all of them have in common is database mail. You can probably guess where I’m going with this. Yep, database mail stopped working. A couple weeks passed before I realized it. Fortunately, out of all the alerts I should have been notified about, none of them were serious.

How would I prevent this happening in the future? I guess I could build another system to monitor my monitoring system. Something like System C, which monitors System B, which monitors System A. But where would that end? System D? System E? Where should the line be drawn? I don’t know that there’s a right answer here, although admittedly, the farther into the alphabet you get, the more absurd it sounds.

At some level, process becomes the answer.  In my case, not before I create a few more systems…

Comments closed

KB2919355

Published 2016-10-12 by Kevin Feasel

Allan Hirt notes that you need KB2919355 installed before you can install SQL Server 2016 on Windows Server 2012 R2 or Windows 8.1:

In my case, I created a new VM with a fresh installation of Windows Server 2012 R2. I also ran Windows Update to ensure it had everything Windows Server thought it required. Figure 3 reflects this status.

As you can see in Figure 4, KB2919355 is not listed as one of the ones WU installed, so it has to be an optional update.

Looking at the list of optional updates in Windows Update in Figure 5, 2919355 is not shown. This means you need to download and install it manually.

It’s never quite as easy as “just run this patch,” so do read on for another gotcha.

Comments closed

Kafka Consumer Group Assignment

Published 2016-10-11 by Kevin Feasel

David Brinegar discusses how consumers within an Apache Kafka consumer group get assigned work:

Or one might want some assignment that results in uniform workloads, based on the number of messages in each partition.  But until we have pluggable assignment functions, the reference implementation has a straightforward assignment strategy called Range Assignment.  There is also a newer Round Robin assignor which is useful for applications like Mirror Maker, but most applications just use the default assignment algorithm.

The Range Assignor tries to land on a uniform distribution of partitions, at least within each topic, while at the same time avoiding the need to coordinate and bargain between nodes.  This last goal, independent assignment, is done by each node executing a fixed algorithm:  sort the partitions, sort the consumers, then for each topic take same-sized ranges of partitions for each consumer.  Where the sizes cannot be the same, the consumers at the beginning of the sorted list will end up with one extra partition.  With this algorithm, each application node can see the entire layout by itself, and from there take up the right assignments.

Click through to see an example of how this is implemented.

Comments closed

Dockerizing ASP.Net Applications

Published 2016-10-11 by Kevin Feasel

Elton Stoneman shows how to package an ASP.Net web application into a Docker image:

It’s how you start to package “legacy” ASP.NET apps in Docker images, so you can run them in containers on Windows 10 and Windows Server 2016. Once you’ve packaged your app into a container image you have:

  • a central artifact which dev and ops teams can work with, which helps you transition to DevOps;

  • an app that runs the same on your laptop, on the server, on Azure, on AWS, which helps you move to the cloud;

  • an app platform which supports distributed systems, which helps you break down the monolith into microservices.

This is part one of a series, but if you read through this post, you’ll end up with a fully-functional app.

Comments closed

Scheduler Timing

Published 2016-10-11 by Kevin Feasel

Ewald Cress continues his look at schedulers:

To simplify things initially, we’ll forget about hidden schedulers and assume hard CPU affinity. That gives us an execution environment that looks like this:

  • Each CPU is physically tied to a scheduler.

  • Therefore, out of all the workers in the system, there is a subset of workers that will only run on that CPU.

  • Workers occasionally hand over control of their CPU to a different worker in their scheduler.

  • At any given moment, each CPU is expected to be running a worker that does something of interest to the middle or upper layers of SQL Server.

  • Some of this useful work will be done on behalf of the worker’s scheduler siblings.

  • However, a (hopefully) tiny percentage of a worker’s time is spent within the act of scheduling.

As usual, this is worth the read.

Comments closed

What Is Kafka?

Published 2016-10-11 by Kevin Feasel

I start a new series on Apache Kafka:

The broker serves several purposes:

  1. Know who the producers are and who the consumers are.  This way, the producers don’t care who exactly consumes a message and aren’t responsible for the message after they hand it off.
  2. Buffer for performance.  If the consumers are a little slow at the moment but don’t usually get overwhelmed, that’s okay—messages can sit with the broker until the consumer is ready to fetch.
  3. Let us scale out more easily.  Need to add more producers?  That’s fine—tell the broker who they are.  Need to add consumers?  Same thing.
  4. What about when a consumer goes down?  That’s the same as problem #2:  hold their messages until they’re ready again.

So brokers add a bit of complexity, but they solve some important problems.  The nice part about a broker is that it doesn’t need to know anything about the messages, only who is supposed to receive it.

This is an introduction to the product and part one of an eight-part series.

Comments closed

Dashboards Or Reports

Published 2016-10-11 by Kevin Feasel

Reza Rad compares dashboards to reports:

Dashboard: General

Stephen Few‘s definition of Dashboard: A dashboard is a visual display of the most important information needed to achieve one or more objectives; consolidated and arranged on a single screen so the information can be monitored at a glance.

Report: General

A Report on the other hand is any informational work. This information can be at any format. Table, Chart, text, number or anything else.

Reza then ties it back to Power BI, showing how to take advantage of both of these concepts.

Comments closed

Interactive Graphics With ggiraph

Published 2016-10-11 by Kevin Feasel

David Smith sheds some light on the ggiraph project:

R’s ggplot2 package is a well-known tool for producing beautiful static data visualizations that you can include in a printed report. But what if you want to include a ggplot2 graphic on a webpage and provide the ability for the user to interact with the data? The ggiraph package by David Gohel  (available for installation via CRAN). WIth ggiraph, you can take an existing ggplot2 bar chart, scatterplot, boxplot, map, or many other types of chart and add one or both of the following iteractions:

  • Display a tooltip of your choice (e.g. data values or labels) when the cursor hovers over sections of the chart

  • Perform an action (a javascript function you provide: jump to another page, for example) when the viewer clicks on an element of the chart

I like it.

Comments closed

Identity As A Service

Published 2016-10-11 by Kevin Feasel

Cristian Satnic argues that we should look at Identity as a Service solutions for our applications:

What exactly is Azure Active Directory B2C?

  • Cloud identity service with support for social accounts and app-specific (local) accounts

  • For enterprises and ISVs building consumer facing web, mobile & native apps

  • Builds on Azure Active Directory – a global identity service serving hundreds of millions of users and billions of sign-ins per day (same directory system used by Microsoft online properties – Office 365, XBox Live and so on)

  • Worldwide, highly-available, geo-redundant service – globally distributed directory across all of Microsoft Azure’s datacenters

I am a big fan of OAuth and making it easy for line-of-business developers to deal with authentication (lest they get harebrained ideas like rolling their own encryption algorithms).

Comments closed

Word Cloud Visual

Published 2016-10-11 by Kevin Feasel

Devin Knight shows off the word cloud custom visual in Power BI:

Key Takeaways

  • Great for parsing unstructured data

  • Utilize stop words to remove commonly used filler words like a, the, an, etc…

    • You can use the default stop word that are provided and add your own that you would like to remove from the visual.

  • The size of the words in the visual tell you how frequently the word is used.

Cf. yesterday’s word cloud example.  I’m not sure how truly valuable word clouds are for visualization purposes, but at least they’re fun to peruse.

Comments closed