ksh24865 opened a new pull request, #48547:
URL: https://github.com/apache/airflow/pull/48547
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## Refactor Variable.set Method to Use Upsert Instead of Delsert
This pull request refactors the `Variable.set` method to replace the current
delsert pattern (delete followed by insert) with an upsert approach, addressing
key reliability and efficiency issues.
### Key Changes:
#### 1. Preventing Unique Constraint Errors
When `set` is called repeatedly within a single process, the existing
delsert pattern can trigger `UNIQUE constraint` violations. This occurs when a
`DELETE` operation has not been flushed or committed before a subsequent
`INSERT` is attempted — even within the same session — leading to conflicts.
Example error message:
```
sqlalchemy.exc.IntegrityError: (psycopg2.errors.UniqueViolation) duplicate
key value violates unique constraint "variable_key_key"
DETAIL: Key (key)=(dummy_variable_key_for_test) already exists.
[SQL: INSERT INTO variable (key, val, description, is_encrypted) VALUES
(%(key)s, %(val)s, %(description)s, %(is_encrypted)s) RETURNING variable.id]
[parameters: {'key': 'dummy_variable_key_for_test', 'val':
'dummy_variable_value_for_test', 'description': None, 'is_encrypted': True}]
(Background on this error at: https://sqlalche.me/e/14/gkpj)
```
<img width="1740" alt="image"
src="https://github.com/user-attachments/assets/8bdec103-6037-47cb-9817-9beb0e5f5979";
/>
#### 2. Reducing Unnecessary Transactions
The previous delsert pattern always executed both a DELETE and an INSERT,
even when the variable already existed. This introduced unnecessary write
operations and transactional overhead.
By switching to an update-or-insert approach, the common case — where a
variable already exists — now results in a single UPDATE instead of a full row
replacement. This reduces the number of write operations and improves overall
efficiency without changing behavior.
Please review the changes and let me know if there are any questions or
further improvements needed.
Feel free to adjust the wording to better fit your style, or let me know if
you'd like me to make any changes.
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