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From Alex Guziel <alex.guz...@airbnb.com.INVALID>
Subject Re: Fundamental change - Separate DAG name and id.
Date Mon, 24 Sep 2018 22:19:50 GMT
I think decoupling dag_id and display name could be confusing and
cumbersome. As for readme, DAG already has a field called description which
I think is close to what Alex is describing (I believe it is displayed by
the UI).

On Mon, Sep 24, 2018 at 3:12 PM Alex Tronchin-James 949-412-7220 <
alex.n.james@gmail.com> wrote:

> Re: [Brian Greene] "How does filename matter?  Frankly I wish the filename
> was REQUIRED to be the dag name so people would quit confusing themselves
> by mismatching them !"
>
> FWIW in the Facebook predecessor to airflow, the file path/name WAS the dag
> name. E.g. if your dag resided in best_team/new_project/sweet_dag.py then
> the dag name would be best_team.new_project.sweet_dag
> All tasks were identified by their variable name after that prefix: E.g. if
> best_team.new_project.sweet_dag defines an operator in a variable named
> task1, then the respective task_id is
> best_team.new_project.sweet_dag.task1.
>
> Airflow provides additional flexibility to specify DAG and task names to
> avoid the sometimes annoyingly long task names this resulted in and allow
> DAG/task names without forcing a code directory structure and python's
> variable naming restrictions, and I think this is a Good Thing.
>
> It seems like airflowuser is trying to provide additional metadata beyond
> the DAG/task names (so far, a DAG 'title' distinct from the ID). I've
> provided this through a README.md included in the DAG source directory, but
> maybe it would be a win to instead add a DAG parameter named 'readme' of
> string type which can include a docstring or even markdown to provide any
> desired additional metadata? This could then be displayed by the UI to
> simplify access to any such provided DAG documentation.
>
> 🍿
>
>
>
> On Thu, Sep 20, 2018 at 10:45 PM Brian Greene <
> brian@heisenbergwoodworking.com> wrote:
>
> > Prior to using airflow for much, on first inspection, I think I may have
> > agreed with you.
> >
> > After a bit of use I’d agree with Fokko and others - this isn’t really a
> > problem, and separating them seems to do more harm than good related to
> > deployment.
> >
> > I was gonna stop there, but why?
> >
> > You can add a task to a dag that’s deployed and has run and still view
> > history.  The “new” task shows up white Squares in the old dags.  nobody
> > said you’re required to also rename the dag when you do so this.  If your
> > process or desire or design determines you need to rename it, well then
> by
> > definition... isn’t it a new thing without a history?  Airflow is
> > implementing exactly that.
> >
> > One could argue that renaming to reflect exact purpose is good practice.
> > Yes, I’d agree, but again following that logic if it’s a small enough
> > change to “slip in” then the name likely shouldn’t change.  If it’s big
> > enough I want to change the name then it’s a big enough change that I’m
> > functionally running something “new”, and I expect to need to account for
> > that.  Airflow is enforcing that logic by coupling the name to the
> > deployment of what you said was a new process.
> >
> > One might put forth that changing the name to be more descriptive In the
> > ui makes it easier for support staff.  I think perhaps if that’s your
> > challenge it’s not airflow that’s a problem.  Dags are of course
> documented
> > elsewhere besides their name, right?  Yeah it’s self documenting (and the
> > graphs are cool), but I have to assume there’s something besides the NAME
> > to tell people what it does.  Additionally, far more than the name is
> > required for even an operator or monitor watcher to take action - you
> don’t
> > expect them to know which tasks to rerun or how to troubleshoot failures
> > just based on your “now most descriptive name in the UI” do you?
> >
> > I spent time In an informatica shop where all the jobs were numbered.
> > Numbered.  Let’s be more exact... their NAMES were NUMBERS like 56709.
> > Terrible, but 100% worked, because while a descriptive name would have
> been
> > useful, the name is the thing that’s supposed to NOT CHANGE (see code of
> > Abibarshim), and all the other information can attach to that in places
> > where you write... other information.  People would curse a number “F’ing
> > 6291 failed again” - everyone knew what they were talking about.. I
> digress.
> >
> >  You might decide to document “dag ID 12” or just “12” on your wiki - I’m
> > going to document “daily_sales_import”.  And when things start failing at
> > 3am it’s not my dag “56” that’s failing, it’s the sales_export dag.  But
> if
> > you document “12”, that’s still it’s name, and it’d better be 12 in all
> > your environments and documents.  This also means the actual db IDs from
> > your proposal are almost certainly NOT the same across your environments,
> > making the 12 unchangeable name!
> >
> > There are lots of languages (most of them) where the name of a thing is
> > important and hard to change.  It’s not a bad thing, and I’d assume that
> > deploying a thing by name has some significance in many systems.  Go
> rename
> > a class in... pick a language... tell me how that should be easier to do
> > willy-nilly so it’s easier In the UI.
> >
> > I suppose you could view it as a limitation, But i don’t think you’ve
> > illuminated a single use case where it’s an actual technical constraint
> or
> > limitation.
> >
> > The BEST argument against the current implementation is db performance.
> > It’s a hogwash argument.  Basic key indexes on low cardinality string
> > columns are plenty fast for the airflow workload, and if your task load
> is
> > so high airflow can’t keep up or your seeing super-fast tasks and airflow
> > db/tracking latency is too much... perhaps a messaging or queue
> processing
> > solution is better suited to those workloads.  We see scheduler
> bottlenecks
> > long before the database for our “quick task” scenarios.  Additionally,
> > reading through this list you’ll find people running airflow at
> substantial
> > scale - I’ve not seen anyone complaining of production performance issues
> > based on this design decision.   At first I hated it.  String keys are
> > dirty, we’re all taught that as good little programmers.  Except when
> > performance won’t be a huge consideration since it’s not OLTP and easy of
> > queryabilty is more important because it’s a growing system... good
> > decision - whoever made it.
> >
> > How does filename matter?  Frankly I wish the filename was REQUIRED to be
> > the dag name so people would quit confusing themselves by mismatching
> them
> > !   We’ve renamed dag files with no issue as long as the content doesn’t
> > change, so again, not a real use case.  And really - name your stuff
> > careful before you get to prod man.
> >
> > I gotta ask - airflowuser - are you gonna use airflow for anything, or
> > just poke it with a stick from a distance and ask semi-inane questions of
> > these fine folks that wrote and spend time working on this cool piece of
> > kit?
> >
> > B
> >
> > Sent from a device with less than stellar autocorrect
> >
> > > On Sep 20, 2018, at 3:12 PM, Driesprong, Fokko <fokko@driesprong.frl>
> > wrote:
> > >
> > > I like the dag_id for both the name and as an unique identifier. If you
> > > change the dag in such a way, that it deserves a new name, you probably
> > > want to create a new dag anyway. If you want to give some additional
> > > context, you can use the description field:
> > >
> >
> https://github.com/apache/incubator-airflow/blob/master/airflow/models.py#L3131-L3132
> > >
> > > The name of the file of dag does not have any influence.
> > >
> > > My 2¢
> > >
> > > Cheers, Fokko
> > >
> > > Op do 20 sep. 2018 om 19:40 schreef James Meickle
> > > <jmeickle@quantopian.com.invalid>:
> > >
> > >> I'm personally against having some kind of auto-increment numeric ID
> for
> > >> DAGs. While this makes a lot of sense for systems where creation is a
> > >> database activity (like a POST request), in Airflow, DAG creation is
> > >> actually a code ship activity. There are all kinds of complex
> scenarios
> > >> around that:
> > >>
> > >> - I revert a commit and a DAG disappears or is renamed
> > >> - I run the same file, twice, with multiple parameters to create two
> > DAGs
> > >> - I create the DAG in both staging and prod, but they wind up with
> > >> different IDs
> > >>
> > >> It's just too hard to automatically track these scenarios.
> > >>
> > >> If we really wanted to put something like this in place, it would
> first
> > >> make more sense to decouple DAG creation from code shipping, and
> instead
> > >> prefer creation of a DAG outside of code (but with a definition that
> > >> references which git repo/committish/file/arguments/etc. to use). Then
> > if
> > >> you do something like rename a file, the DAG breaks, but at least
> still
> > >> exists in the db with that ID and history still makes sense once you
> > update
> > >> the DAG definition with the new code location.
> > >>
> > >> On Thu, Sep 20, 2018 at 4:52 AM airflowuser
> > >> <airflowuser@protonmail.com.invalid> wrote:
> > >>
> > >>> Hi,
> > >>> though this could have been explained on Jira I think this should be
> > >>> discussed first.
> > >>>
> > >>> The problem:
> > >>> Airflow mixes DAG name with id. It uses same filed for both purposes.
> > >>>
> > >>> I assume that most of you use the dag_id to describe what the DAG
> > >> actually
> > >>> does.
> > >>> For example:
> > >>>
> > >>> dag = DAG(
> > >>>    dag_id='cost_report_daily',
> > >>> ...
> > >>> )
> > >>>
> > >>> This dag_id is reflected to the dag id column in the UI.
> > >>> Now, lets say that you want to add another task to this specific dag
> -
> > >> You
> > >>> are to be extremely careful when you change the dag_id to represent
> the
> > >> new
> > >>> functionality for example : dag_id='cost_expenses_reports_daily' .
> This
> > >>> will break the history of the DAG.
> > >>>
> > >>> Or even with simpler use case.. the user just want to change the name
> > he
> > >>> sees on the UI.
> > >>>
> > >>> I suggest to have a discussion if the dag_id should be split into id
> > (an
> > >>> actual id) and name to reflect what it does. When the "connection"
is
> > >> done
> > >>> by id's  - names can change as much as you want without breaking
> > >> anything.
> > >>> essentially it becomes a field uses for display purpose  only.
> > >>>
> > >>> * I didn't mention also the issue of DAG file name which can also
> cause
> > >>> trouble if someone wants to change it.
> > >>>
> > >>> Sent with [ProtonMail](https://protonmail.com) Secure Email.
> > >>
> >
>

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