FrankYang0529 opened a new pull request, #72554: URL: https://github.com/apache/airflow/pull/72554
## Why - #52325 moved the single-value XCom lookups from `Query.first()` to `session.scalars(...).first()` / `session.execute(...).first()`, and the explicit `.limit(1)` was dropped in review as redundant with `first()` (https://github.com/apache/airflow/pull/52325#discussion_r2222463044). - That is true for the legacy `Query.first()`, which adds `LIMIT 1` to the SQL. `Result.first()` does not: its docstring says "no limit is applied to the SQL query", and with a buffering DBAPI driver "all rows will be sent to the Python process and all but the first row will be discarded" (https://github.com/sqlalchemy/sqlalchemy/blob/rel_2_0_52/lib/sqlalchemy/engine/result.py#L1447-L1453). ## How - Add `.limit(1)` back on the four single-row lookups: `get_mapped_xcom_by_index` and `get_xcom`, `TaskInstance.xcom_pull`, and the `create_xcom_entry`. ## Verification Set up: ``` uv sync --package apache-airflow-core uv pip install -e shared/*/ ``` Unit test: ``` uv run --package apache-airflow-core pytest \ airflow-core/tests/unit/api_fastapi/execution_api/versions/head/test_xcoms.py \ airflow-core/tests/unit/models/test_taskinstance.py \ airflow-core/tests/unit/api_fastapi/core_api/routes/public/test_xcom.py ``` <!-- SPDX-License-Identifier: Apache-2.0 https://www.apache.org/licenses/LICENSE-2.0 --> <!-- Thank you for contributing! Please provide above a brief description of the changes made in this pull request. Write a good git commit message following this guide: https://chris.beams.io/posts/git-commit/ Please make sure that your code changes are covered with tests. And in case of new features or big changes remember to adjust the documentation. For user-facing UI changes, please attach before/after screenshots (or a short screen recording) so reviewers can assess the visual impact. Feel free to ping (in general) for the review if you do not see reaction for a few days (72 Hours is the minimum reaction time you can expect from volunteers) - we sometimes miss notifications. In case of an existing issue, reference it using one of the following: * closes: #ISSUE * related: #ISSUE --> --- ##### Was generative AI tooling used to co-author this PR? <!-- If generative AI tooling has been used in the process of authoring this PR, please change below checkbox to `[X]` followed by the name of the tool, uncomment the "Generated-by". --> - [X] Yes - Claude Code <!-- Generated-by: [Tool Name] following [the guidelines](https://github.com/apache/airflow/blob/main/contributing-docs/05_pull_requests.rst#gen-ai-assisted-contributions) --> --- * Read the **[Pull Request Guidelines](https://github.com/apache/airflow/blob/main/contributing-docs/05_pull_requests.rst#pull-request-guidelines)** for more information. Note: commit author/co-author name and email in commits become permanently public when merged. * For fundamental code changes, an Airflow Improvement Proposal ([AIP](https://cwiki.apache.org/confluence/display/AIRFLOW/Airflow+Improvement+Proposals)) is needed. * When adding dependency, check compliance with the [ASF 3rd Party License Policy](https://www.apache.org/legal/resolved.html#category-x). * For significant user-facing changes create newsfragment: `{pr_number}.significant.rst`, in [airflow-core/newsfragments](https://github.com/apache/airflow/tree/main/airflow-core/newsfragments). You can add this file in a follow-up commit after the PR is created so you know the PR number. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
