> On 24 Sep 2018, at 23:12, Alex Tronchin-James 949-412-7220 > <alex.n.ja...@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.
You mean like https://airflow.apache.org/concepts.html#documentation-notes <https://airflow.apache.org/concepts.html#documentation-notes> ? ✨ > > 🍿 > > > > On Thu, Sep 20, 2018 at 10:45 PM Brian Greene < > br...@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 <fo...@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 >>> <jmeic...@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 >>>> <airflowu...@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. >>>> >>
