What Is High-Cardinality in Monitoring?

High-cardinality in SQL refers to highly differentiated data for a given column. (Although “relatively unique” is not grammatical, that is one way to say it.) When there are many different possible values for a given column, that is high-cardinality. In the context of monitoring, what is high-cardinality?

In monitoring like relational databases, cardinality refers to the number of elements in a set (consistent with the mathematical definition https://www.dictionary.com/browse/cardinality).

What Can Cause an Application to Run Slowly?

Problem scenario
You support an existing application and its servers. It is experiencing slowness as the users are complaining about its performance. What are some potential root causes of this slowness?

Possible Solutions

  • The slowness is caused by the client. A user’s workstation has something wrong with it (e.g., malware, or it is trying to run too many applications at once).

How Do You Configure Email Alerts for AWS Spending Thresholds of Specific Dollar Amounts?

Problem scenario
Sometimes you forget what is running in AWS. You want to be notified when you have spent a certain amount of money. How do you set up a notification in your AWS account that will apprise you when you have have spent over a certain amount of money for a given month?


  1. Log into the AWS Management Console (aka the web UI).

How Can You Use CloudTrail for the First Time in Your AWS Account?

Problem scenario
You want to log or monitor AWS activity (e.g., AWS Management Console, AWS CLI, and/or AWS SDK actions). You do not want encryption because you are just testing it out. How do you use CloudTrail to do this?


  1. Log into AWS.
  2. Go to this link: https://console.aws.amazon.com/cloudtrail/
  3. Click “Create a trail”
  4. Enter a descriptive name for your trail.

What Do You Do If CloudWatch Metrics Are Not Showing Up in the Dashboard?

Problem scenario
You used a .json file and the AWS CLI to configure customized metrics. When you go to the GUI you do not see the graphs. The commands that were run with the .json file completed without errors or problems. How do you get the web console to show the metrics you configured for various AWS components?

Possible Solution #1
CloudWatch metrics are not all necessarily graphed.

What Are the Recommended Practices of Monitoring?

AWS’s Five Pillars of Well-Architected Framework recommend monitoring as a component of three of the pillars (operational excellence, reliability and performance efficiency).

There is no question that monitoring is important inside or outside of a public cloud. What patterns or traits might a good centralized monitoring system have (consistent with some phrase as “best practices”)?

Here are 15 characteristics of good monitoring.

How Do You Install Sysdig in an Existing Debian-Based Docker Container?

Problem scenario
You want to monitor Docker containers.  Therefore you want to install Sysdig to try it out.  How do you install Sysdig in a pre-existing Docker container?

Run these three commands:
apt-get -y update
apt-get -y install curl
curl -s https://s3.amazonaws.com/download.draios.com/stable/install-sysdig | bash