getredash/redash

Can't delete a data source if one of the queries references query result from it but uses a different data source

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#3843 opened on May 29, 2019

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 (6 comments) (1 reaction) (1 assignee)Python (24,845 stars) (4,236 forks)batch import
BackendBughelp wanted

Description

Issue Summary

When you have the following situation:

Query A references query result from data source A, but itself references data source B.

You will not be able to delete data source A, because it will fail to delete the query results using it.

Steps to Reproduce

The way the above can happen is if:

  1. You execute query A while it uses data source A and update it to use data source B.
  2. If the data source update happens right after this query was executed but before we actually update the query result reference.

It's an edge case, but happened already twice for people who reported it.

The correct solution here is to update the latest_query_data_id reference to get nullified if the query result is deleted.

Technical details:

  • Redash Version: 7

Contributor guide

Tech stack
python
Domain
backend
Issue type
bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
half day
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
Python programmingSQLAlchemy ORMDatabase concepts
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
45
Research direction
Examine the QueryResult model and the deletion logic in redash/models/ init .py around lines 304-309. The issue suggests nullifying the latest query data id when a query result is deleted. Review the database constraints and ensure no foreign key issues. Consider adding a migration if needed. Also check if there are any existing tests for this scenario.