Apache Superset, wrong calculation on percentage metrics columns

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Summary

The issue with Apache Superset version 6.0 (and also present in version 5) involves percentage metrics columns not calculating percentages correctly when the “show summary” option is enabled. This results in columns displaying only zeros instead of the expected percentage values.

Root Cause

The root cause of this issue can be attributed to several factors, including:

  • Incorrect configuration of the percentage metrics column
  • Incompatible data types being used for the calculation
  • Insufficient data to perform the percentage calculation
  • Buggy implementation of the percentage metrics feature in Superset

Why This Happens in Real Systems

This issue occurs in real systems due to:

  • Complex data pipelines that can introduce errors or inconsistencies
  • Inadequate testing of the Superset installation and configuration
  • Version compatibility issues between different components of the system
  • Human error in configuring or using the Superset interface

Real-World Impact

The impact of this issue includes:

  • Inaccurate insights and decision-making based on incorrect data
  • Wasted time and resources trying to troubleshoot and resolve the issue
  • Loss of trust in the Superset platform and its ability to provide reliable data
  • Delays in business operations due to the inability to rely on accurate data

Example or Code (if necessary and relevant)

from superset import SupersetClient

# Create a new Superset client
client = SupersetClient()

# Define the percentage metrics column
column = {
    "column_name": "percentage_column",
    "data_type": "percentage",
    "show_summary": True
}

# Create the column in Superset
client.create_column(column)

How Senior Engineers Fix It

Senior engineers fix this issue by:

  • Verifying the configuration of the percentage metrics column
  • Checking the data types and ensuring they are compatible
  • Testing the calculation with sample data to identify any issues
  • Updating the Superset version or applying patches to resolve any known bugs
  • Implementing workarounds or custom solutions if necessary

Why Juniors Miss It

Junior engineers may miss this issue due to:

  • Lack of experience with Superset and its configuration options
  • Insufficient understanding of data types and compatibility issues
  • Inadequate testing and troubleshooting skills
  • Overreliance on default settings without verifying their correctness
  • Failure to consult documentation or seek help from more experienced colleagues

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