iosif2 opened a new issue, #53551:
URL: https://github.com/apache/airflow/issues/53551
### Apache Airflow version
3.0.3
### If "Other Airflow 2 version" selected, which one?
_No response_
### What happened?
## This issue addresses error encountered when deleting dags via both the
CLI and the web UI.
### 1. ForeignKeyViolation on backfill table deletion
- However executing the deletion twice as separate operations resolves the
issue and allows for successful deletion.
- Root Cause: This error occurs randomly due to how the delete_dag function
operates. I suspect that get_sqla_model_classes does not consistently return
models in the correct dependency order.
#### Command Line Output for this error:
```
root@f6650f6a4c58:/opt/airflow# airflow dags delete test_dag2
This will drop all existing records related to the specified DAG. Proceed?
(y/n)y
[2025-07-18T13:21:57.427+0000] {delete_dag.py:53} INFO - Deleting DAG:
test_dag2
Traceback (most recent call last):
File "/usr/local/lib/python3.10/site-packages/sqlalchemy/engine/base.py",
line 1910, in _execute_context
self.dialect.do_execute(
File
"/usr/local/lib/python3.10/site-packages/sqlalchemy/engine/default.py", line
736, in do_execute
cursor.execute(statement, parameters)
psycopg2.errors.ForeignKeyViolation: update or delete on table "backfill"
violates foreign key constraint "dag_run_backfill_id_fkey" on table "dag_run"
DETAIL: Key (id)=(2) is still referenced from table "dag_run".
The above exception was the direct cause of the following exception:
Traceback (most recent call last):
File "/usr/local/bin/airflow", line 10, in <module>
sys.exit(main())
File "/opt/airflow/airflow-core/src/airflow/__main__.py", line 55, in main
args.func(args)
File "/opt/airflow/airflow-core/src/airflow/cli/cli_config.py", line 48,
in command
return func(*args, **kwargs)
File "/opt/airflow/airflow-core/src/airflow/utils/cli.py", line 113, in
wrapper
return f(*args, **kwargs)
File
"/opt/airflow/airflow-core/src/airflow/utils/providers_configuration_loader.py",
line 54, in wrapped_function
return func(*args, **kwargs)
File "/opt/airflow/airflow-core/src/airflow/cli/commands/dag_command.py",
line 103, in dag_delete
message = api_client.delete_dag(dag_id=args.dag_id)
File "/opt/airflow/airflow-core/src/airflow/api/client/local_client.py",
line 74, in delete_dag
count = delete_dag.delete_dag(dag_id)
File "/opt/airflow/airflow-core/src/airflow/utils/session.py", line 100,
in wrapper
return func(*args, session=session, **kwargs)
File "/opt/airflow/airflow-core/src/airflow/api/common/delete_dag.py",
line 70, in delete_dag
count += session.execute(
File "/usr/local/lib/python3.10/site-packages/sqlalchemy/orm/session.py",
line 1717, in execute
result = conn._execute_20(statement, params or {}, execution_options)
File "/usr/local/lib/python3.10/site-packages/sqlalchemy/engine/base.py",
line 1710, in _execute_20
return meth(self, args_10style, kwargs_10style, execution_options)
File "/usr/local/lib/python3.10/site-packages/sqlalchemy/sql/elements.py",
line 334, in _execute_on_connection
return connection._execute_clauseelement(
File "/usr/local/lib/python3.10/site-packages/sqlalchemy/engine/base.py",
line 1577, in _execute_clauseelement
ret = self._execute_context(
File "/usr/local/lib/python3.10/site-packages/sqlalchemy/engine/base.py",
line 1953, in _execute_context
self._handle_dbapi_exception(
File "/usr/local/lib/python3.10/site-packages/sqlalchemy/engine/base.py",
line 2134, in _handle_dbapi_exception
util.raise_(
File "/usr/local/lib/python3.10/site-packages/sqlalchemy/util/compat.py",
line 211, in raise_
raise exception
File "/usr/local/lib/python3.10/site-packages/sqlalchemy/engine/base.py",
line 1910, in _execute_context
self.dialect.do_execute(
File
"/usr/local/lib/python3.10/site-packages/sqlalchemy/engine/default.py", line
736, in do_execute
cursor.execute(statement, parameters)
sqlalchemy.exc.IntegrityError: (psycopg2.errors.ForeignKeyViolation) update
or delete on table "backfill" violates foreign key constraint
"dag_run_backfill_id_fkey" on table "dag_run"
DETAIL: Key (id)=(2) is still referenced from table "dag_run".
[SQL: DELETE FROM backfill WHERE backfill.dag_id = %(dag_id_1)s RETURNING
backfill.id]
[parameters: {'dag_id_1': 'test_dag2'}]
(Background on this error at: https://sqlalche.me/e/14/gkpj)
```
### 2. ForeignKeyViolation on other tables (related to dag_version)
- Root Cause: It suggests that deleting dag_version records is blocked
because they are still referenced by the task_instance table.
- Proposed Solution: I believe the RESTRICT ON DELETE behavior is
unnecessary for this table; thus, I have modified it to CASCADE to resolve this
issue.
#### Command Line Output for this error:
```
root@f6650f6a4c58:/opt/airflow/airflow-core/src/airflow# airflow dags delete
test_dag1
This will drop all existing records related to the specified DAG. Proceed?
(y/n)y
[2025-07-18T13:39:21.439+0000] {delete_dag.py:53} INFO - Deleting DAG:
test_dag1
Traceback (most recent call last):
File "/usr/local/lib/python3.10/site-packages/sqlalchemy/engine/base.py",
line 1910, in _execute_context
self.dialect.do_execute(
File
"/usr/local/lib/python3.10/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)=(01981dc1-c244-7368-bd32-44242bc82280) is still referenced
from table "task_instance".
The above exception was the direct cause of the following exception:
Traceback (most recent call last):
File "/usr/local/bin/airflow", line 10, in <module>
sys.exit(main())
File "/opt/airflow/airflow-core/src/airflow/__main__.py", line 55, in main
args.func(args)
File "/opt/airflow/airflow-core/src/airflow/cli/cli_config.py", line 48,
in command
return func(*args, **kwargs)
File "/opt/airflow/airflow-core/src/airflow/utils/cli.py", line 113, in
wrapper
return f(*args, **kwargs)
File
"/opt/airflow/airflow-core/src/airflow/utils/providers_configuration_loader.py",
line 54, in wrapped_function
return func(*args, **kwargs)
File "/opt/airflow/airflow-core/src/airflow/cli/commands/dag_command.py",
line 103, in dag_delete
message = api_client.delete_dag(dag_id=args.dag_id)
File "/opt/airflow/airflow-core/src/airflow/api/client/local_client.py",
line 74, in delete_dag
count = delete_dag.delete_dag(dag_id)
File "/opt/airflow/airflow-core/src/airflow/utils/session.py", line 100,
in wrapper
return func(*args, session=session, **kwargs)
File "/opt/airflow/airflow-core/src/airflow/api/common/delete_dag.py",
line 70, in delete_dag
count += session.execute(
File "/usr/local/lib/python3.10/site-packages/sqlalchemy/orm/session.py",
line 1717, in execute
result = conn._execute_20(statement, params or {}, execution_options)
File "/usr/local/lib/python3.10/site-packages/sqlalchemy/engine/base.py",
line 1710, in _execute_20
return meth(self, args_10style, kwargs_10style, execution_options)
File "/usr/local/lib/python3.10/site-packages/sqlalchemy/sql/elements.py",
line 334, in _execute_on_connection
return connection._execute_clauseelement(
File "/usr/local/lib/python3.10/site-packages/sqlalchemy/engine/base.py",
line 1577, in _execute_clauseelement
ret = self._execute_context(
File "/usr/local/lib/python3.10/site-packages/sqlalchemy/engine/base.py",
line 1953, in _execute_context
self._handle_dbapi_exception(
File "/usr/local/lib/python3.10/site-packages/sqlalchemy/engine/base.py",
line 2134, in _handle_dbapi_exception
util.raise_(
File "/usr/local/lib/python3.10/site-packages/sqlalchemy/util/compat.py",
line 211, in raise_
raise exception
File "/usr/local/lib/python3.10/site-packages/sqlalchemy/engine/base.py",
line 1910, in _execute_context
self.dialect.do_execute(
File
"/usr/local/lib/python3.10/site-packages/sqlalchemy/engine/default.py", line
736, in do_execute
cursor.execute(statement, parameters)
sqlalchemy.exc.IntegrityError: (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)=(01981dc1-c244-7368-bd32-44242bc82280) is still referenced
from table "task_instance".
[SQL: DELETE FROM dag_version WHERE dag_version.dag_id = %(dag_id_1)s
RETURNING dag_version.id]
[parameters: {'dag_id_1': 'test_dag1'}]
(Background on this error at: https://sqlalche.me/e/14/gkpj)
```
### What you think should happen instead?
_No response_
### How to reproduce
### 1. ForeignKeyViolation on backfill table deletion
- Reproduction Steps: first backfill any DAG. Then, execute airflow dags
delete [dag_id]. This error occurs randomly due to how the delete_dag function
operates.
### 2. ForeignKeyViolation on other tables (related to dag_version)
- Reproduction Steps: While I am not entirely certain how to consistently
reproduce this specific error, it appears alongside the backfill deletion error
described above.
### Operating System
macOS 15.5 (24F74)
### Versions of Apache Airflow Providers
_No response_
### Deployment
Docker-Compose
### Deployment details
docker compose with both latest released image and main branch
### Anything else?
I have already opened PR #53501 related to this issue. That PR includes
changes to the ON DELETE behavior for the `dag_run` and `task_instance` tables.
However, modifying the delete_dag function to manually sort the delete target
models would be a better solution than my current approach.
### Are you willing to submit PR?
- [x] Yes I am willing to submit a PR!
### Code of Conduct
- [x] I agree to follow this project's [Code of
Conduct](https://github.com/apache/airflow/blob/main/CODE_OF_CONDUCT.md)
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