apache/airflow

Dashboard summary page shows wrong percentages when a state count exceeds the API cap (1000)

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#67.336 aberto em 22 de mai. de 2026

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affected_version:3.2area:APIarea:UIgood first issuekind:bug

Description

Under which category would you file this issue?

Airflow Core

Apache Airflow version

3.2.1

What happened and how to reproduce it?

The Dashboard's Historical Metrics section displays running, succeeded, waiting, and failed task instances / Dag runs with a percentage bar. These percentages are calculated in the frontend by dividing each state's count by the sum of all state counts (total):

The API endpoint "/ui/dashboard/historical_metrics_data" internally limits/caps the state count at STATE_COUNT_CAP = 1000 to limit the SQL query row count for performance reasons, so a maximum count of 1000 is returned.

The bug: The total used to calculate percentages is computed from the capped API values. So if success has 2500 and failure has 7 entries but the API returns 1000 for success, the computed total is 1007 instead of 2507. This wrong total results in wrong percentages.

What you think should happen instead?

The UI should show the correct percentage or no percentage for capped values, but not the wrong percentages.

There are two possible ways to fix this:

  1. Return real counts from the API
  2. Hide percentages in the frontend when any state is capped

Returning the real counts from the API with a huge amount of task instances can be significantly slower than the current approach, which uses the limit per state for a good reason: to ensure a fast response even on huge datasets. The downside of keeping the cap is that the frontend cannot compute correct percentages when any state exceeds it, since the total cannot be computed correctly.

I would be happy to file a PR about this issue, but want to discuss those tradeoffs first with the community.

Best, Stefan

Operating System

Ubuntu 24.04.4 LTS

Deployment

Virtualenv installation

Apache Airflow Provider(s)

No response

Versions of Apache Airflow Providers

No response

Official Helm Chart version

Not Applicable

Kubernetes Version

No response

Helm Chart configuration

No response

Docker Image customizations

No response

Anything else?

No response

Are you willing to submit PR?

  • Yes I am willing to submit a PR!

Code of Conduct

Guia do colaborador

Pilha de tecnologia
pythonreact
Domain
frontendbackend
Tipo Issue
bug
DifficultyDificuldade de implementação estimada para um novo contribuidor, de 1 para alterações muito pequenas a 5 para trabalho de nível especializado.
3
Tempo estimadoUm intervalo de tempo aproximado para um colaborador experiente investigar, implementar, testar e preparar um pull request.
half day
Status da atividadeQuão disponível o issue aparece agora: novo, ativo, obsoleto, bloqueado ou aguardando entrada do mantenedor.
fresh
ClarityCom que clareza o issue explica a mudança esperada, os critérios de aceitação e a próxima etapa.
clear
Prerequisites
PythonReactApache Airflow
Simpatia para novatosUma pontuação de 1 a 100 que estima o quão acessível este issue é para colaboradores iniciantes.
70
Direção de pesquisa
Examine the implementation of the /ui/dashboard/historical metrics data API endpoint and the frontend component that calculates percentages. Consider the tradeoffs between removing the cap to get accurate counts (possibly slower) or modifying the frontend to hide percentages when any state is capped. Engage with maintainers on the issue to decide the preferred direction before implementing.