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https://issues.apache.org/jira/browse/AIRFLOW-5930?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16993866#comment-16993866
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ASF GitHub Bot commented on AIRFLOW-5930:
-----------------------------------------
ashb commented on pull request #6792: [AIRFLOW-5930] Use cached-SQL query
building for hot-path queries
URL: https://github.com/apache/airflow/pull/6792
Make sure you have checked _all_ steps below.
### Jira
- [x] https://issues.apache.org/jira/browse/AIRFLOW-5930
### Description
- [ ] Building the SQL string for this query takes up about 25% of the time
that the DAG parsing process spends, so replacing this one query should help
speed up the rate at which the scheduler can queue tasks.
See https://docs.sqlalchemy.org/en/13/orm/extensions/baked.html for more
info. The docs explain a lot of how/why this works, so rather than rebuilding
them from string 10s of times (once per task per active dag run) we cache the
build SQL string!
I will collect up-to-date performance numbers against master, but this
makes the "dag parsing" process of the scheduler (which creates and updates dag
runs, and creates Task Instances) about 2x quicker:
Concurrent DagRuns | Tasks | Before | After | Speedup
-- | -- | -- | -- | --
2 | 12 | 0.146s (±0.0163s) | 0.074s (±0.0037s) | x1.97
10 | 12 | 1.11s (±0.0171s) | 0.266s (±0.0229s) | x4.17
40 | 12 | 4.28s (±0.101s) | 0.852s (±0.0113s) | x5.02
40 | 40 | 6.72s (±0.067s) | 2.659s (±0.0283s) | x2.53
### Tests
- [x] No new tests, no change in behaviour.
### Commits
- [ ] My commits all reference Jira issues in their subject lines, and I
have squashed multiple commits if they address the same issue. In addition, my
commits follow the guidelines from "[How to write a good git commit
message](http://chris.beams.io/posts/git-commit/)":
1. Subject is separated from body by a blank line
1. Subject is limited to 50 characters (not including Jira issue reference)
1. Subject does not end with a period
1. Subject uses the imperative mood ("add", not "adding")
1. Body wraps at 72 characters
1. Body explains "what" and "why", not "how"
### Documentation
- [ ] In case of new functionality, my PR adds documentation that describes
how to use it.
- All the public functions and the classes in the PR contain docstrings
that explain what it does
- If you implement backwards incompatible changes, please leave a note in
the [Updating.md](https://github.com/apache/airflow/blob/master/UPDATING.md) so
we can assign it to a appropriate release
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> Reduce time spent building SQL strings
> --------------------------------------
>
> Key: AIRFLOW-5930
> URL: https://issues.apache.org/jira/browse/AIRFLOW-5930
> Project: Apache Airflow
> Issue Type: Improvement
> Components: scheduler
> Affects Versions: 2.0.0
> Reporter: Ash Berlin-Taylor
> Assignee: Ash Berlin-Taylor
> Priority: Major
>
> My profling of the scheduler work turned up a lot of cases where the
> scheduler_job/dag parser process was spending a lot of time building (not
> executing!) the SQL string.
> This can be improved with
> https://docs.sqlalchemy.org/en/13/orm/extensions/baked.html
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