Customizing Grafana Histogram Axes for Latency Metrics

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1

I’m using multiple Prometheus histogram metrics following the pattern *_duration_seconds_bucket that represent latency breakdown across my pipeline. These metrics track iterations typically taking ~100ms, and I’m using le=“+Inf” buckets in my queries. Currently displaying this data in Table, Bar Chart, and Histogram panels.
Two issues specifically with the Histogram panel only:

X-axis bucket width: The histogram automatically sets intervals (currently 2.40ms). Is it possible to manually define these intervals (e.g., 0.5ms) through dashboard variables or panel settings?
Y-axis decimal issue: The y-axis shows count values with decimals (0.5, 1.5) which doesn’t make sense for count data. When I set decimals=0 in panel options, it causes duplicate labels on the axis (2-2, 3-3). How can I properly display whole numbers without this duplication?

2

To address the issues you're facing with the Histogram panel in Grafana, let's tackle each one separately:

X-axis Bucket Width

To manually define the bucket width for your histogram, you can adjust the Bucket size option in the histogram panel settings. This allows you to specify the size of each bucket, which can help you achieve the desired granularity, such as 0.5ms intervals. Here's how you can do it:

  1. Open the Panel Editor: Click on the panel title and select "Edit" to open the panel editor.
  2. Navigate to Histogram Options: In the panel editor, look for the "Histogram options" section.
  3. Set Bucket Size: Specify your desired bucket size (e.g., 0.5ms) in the "Bucket size" field. If this field is left empty, Grafana will automatically determine the bucket size.

Y-axis Decimal Issue

The issue with the Y-axis showing decimal values for count data is indeed problematic, as counts should be whole numbers. The duplication of labels when setting decimals to 0 is a known issue. Here are a few potential workarounds:

  1. Check for Updates: Ensure you are using the latest version of Grafana, as this issue might have been addressed in newer releases.

  2. Custom Axis Formatting: If the issue persists, you can try using custom axis formatting options. In the panel editor, under the "Standard options" or "Field" tab, look for options related to axis formatting. You might be able to set a custom format that forces whole numbers.

  3. Workaround with No Value String: As a temporary workaround, you can leave the "No value" string blank to avoid the duplication issue. This means you won't have a custom message when there's no data, but it will prevent the unwanted duplication.

  4. Report or Follow Up on the Issue: If the problem continues and affects your workflow significantly, consider reporting it on Grafana's GitHub issues page or checking if there's an existing issue you can follow for updates.

By adjusting these settings, you should be able to better control the display of your histogram panel and ensure it accurately represents your latency metrics. If you have any further questions or need more detailed guidance, feel free to ask!

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