[PR] Fix KEDA query for Kubernetes Executor [airflow]

["wolfdn (via GitHub)" <gi...@apache.org>]

wolfdn opened a new pull request, #55559:
URL: https://github.com/apache/airflow/pull/55559

   <!--
    Licensed to the Apache Software Foundation (ASF) under one
    or more contributor license agreements.  See the NOTICE file
    distributed with this work for additional information
    regarding copyright ownership.  The ASF licenses this file
    to you under the Apache License, Version 2.0 (the
    "License"); you may not use this file except in compliance
    with the License.  You may obtain a copy of the License at
   
      http://www.apache.org/licenses/LICENSE-2.0
   
    Unless required by applicable law or agreed to in writing,
    software distributed under the License is distributed on an
    "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
    KIND, either express or implied.  See the License for the
    specific language governing permissions and limitations
    under the License.
    -->
   
   <!--
   Thank you for contributing! 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.
   
   Feel free to ping committers for the review!
   
   In case of an existing issue, reference it using one of the following:
   
   closes: #ISSUE
   related: #ISSUE
   
   How to write a good git commit message:
   http://chris.beams.io/posts/git-commit/
   -->
   
   ## Description
   
   We noticed that when using a comparison like the one below for a KEDA query there is an issue with *null* values. Comparisons using '!=' will not return any rows which are *null*.
   
   https://modern-sql.com/caniuse/is-distinct-from
   
   This becomes a problem if there are tasks in the task_instance table which have not explicitly set an *executor* (so they just use the default one). So the issue occurs if the CeleryExecutor is set as default executor and the Kubernetes executor is set as additional (non-default) executor.
   Then task instances which are up to be executed by the Celery executor will not be considered by the KEDA query and KEDA will scale down the worker count to 0 - which means that tasks waiting to be executed by the Celery executor never be executed.
   
   The SQL comparison using "IS DISTINCT FROM" *includes* null values. Like this the KEDA query also works if the Celery Executor is set as default executor and tasks do not explicitly set the Executor field.
   
   
   <!-- Please keep an empty line above the dashes. -->
   ---
   **^ Add meaningful description above**
   Read the **[Pull Request Guidelines](https://github.com/apache/airflow/blob/main/contributing-docs/05_pull_requests.rst#pull-request-guidelines)** for more information.
   In case of fundamental code changes, an Airflow Improvement Proposal ([AIP](https://cwiki.apache.org/confluence/display/AIRFLOW/Airflow+Improvement+Proposals)) is needed.
   In case of a new dependency, check compliance with the [ASF 3rd Party License Policy](https://www.apache.org/legal/resolved.html#category-x).
   In case of backwards incompatible changes please leave a note in a newsfragment file, named `{pr_number}.significant.rst` or `{issue_number}.significant.rst`, in [airflow-core/newsfragments](https://github.com/apache/airflow/tree/main/airflow-core/newsfragments).
   


-- 
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: commits-unsubscribe@airflow.apache.org

For queries about this service, please contact Infrastructure at:
users@infra.apache.org

Re: [PR] Fix KEDA query for Kubernetes Executor [airflow]

["jscheffl (via GitHub)" <gi...@apache.org>]

jscheffl merged PR #55559:
URL: https://github.com/apache/airflow/pull/55559


-- 
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: commits-unsubscribe@airflow.apache.org

For queries about this service, please contact Infrastructure at:
users@infra.apache.org