Andrey Anshin

Looks really nice! I would suggest to keep information about PostgresOperator into the documentation, e.g. in warning block This might help users who try to search PostgresOperator via search engines...

This happen due to log deduplication, which might happen when logs streaming from remote logging https://github.com/apache/airflow/blob/3938f71dfae21c84a3518625543a28ad02edf641/airflow/utils/log/file_task_handler.py#L130-L140

If you have a suggestion how improve logging feel free to raise a PR which will work with any type of existed loggers without breaking changes.

Feel free to fix this behaiviour

> The Postgres instance started reporting many could not obtain lock on row in relation "dag_run" errors: This pretty fine, because Airflow tried to obtain row level lock by utilise...

Correction: `SELECT .. FOR UPDATE NOWAIT` raise this error

> if it always results in an ERROR Are you sure that it is always return an error?

This one use in mini scheduler mechanism, which might fail and it is fine and by design, this just an optimisation mechanism. It might also tried to work concurrently, so...

As measure might be use `skip_locked` instead of `no_wait` both of them non blocking, with differences how it handled internally in DB backend: - SKIP LOCKED: return non locked records...

> yeah, would be great to avoid DB internal error Feel free to fix it. Apache Airflow it is open source project, and every one could contribute changes (fixes/features) back,...