HsiuChuanHsu opened a new pull request, #56567:
URL: https://github.com/apache/airflow/pull/56567
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## Problem
When running `airflow db clean` with a timestamp, the command fails with a
ForeignKeyViolation error when attempting to delete old dag_version records.
```bash
Checking table dag_version
Found 1 rows meeting deletion criteria.
Performing Delete...
Moving data to table _airflow_deleted__dag_version__20251011083345
Traceback (most recent call last):
File "/usr/python/lib/python3.12/site-packages/sqlalchemy/engine/base.py",
line 1910, in _execute_context
self.dialect.do_execute(
File
"/usr/python/lib/python3.12/site-packages/sqlalchemy/engine/default.py", line
736, in do_execute
cursor.execute(statement, parameters)
psycopg2.errors.ForeignKeyViolation: update or delete on table "dag_version"
violates foreign key constraint "task_instance_dag_version_id_fkey" on table
"task_instance"
DETAIL: Key (id)=(018c5e5e-7a8b-7000-8000-000000000001) is still referenced
from table "task_instance".
```
**Why this happened?** Reference to
[reproduction](https://github.com/apache/airflow/issues/56192#issuecomment-3393068953).
We executed the Airflow database cleanup command:
```bash
airflow db clean --clean-before-timestamp "2025-09-21T10:30" --skip-archive
--yes
```
**Cleanup Conditions Check (Clean before 2025-09-21):**
- dag_version (2025-09-01) **meets** the cleanup condition (before
2025-09-21).
- task_instance-1 (2025-09-06) **meets** the cleanup condition (before
2025-09-21).
- task_instance-2 (2025-10-01) **does not meet** the cleanup condition
(after 2025-09-21).
**Resulting Issue:**
The attempt to delete the qualifying `dag_version` failed. This is because
the newer `task_instance-2` record is still referencing it, which triggered a
`RESTRICT` violation.
## Fix
**Refined Cleanup Logic:**
- Before removing a `dag_version`, we must check for any remaining
references.
- If references exist, the `dag_version` will be skipped.
**Chanage**
- Add a `skip_if_referenced_by` parameter to _TableConfig to exclude records
that are
still referenced by other tables during cleanup.
- Added `_build_skip_if_referenced_filter()` function to generate exclusion
conditions
---
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