You could start a [VOTE][PMC ONLY] thread on this topic (
https://www.apache.org/foundation/voting.html). Not sure if that's the best
Apache way of doing things, but seems fine to me. My PMC vote personally
would maybe be to switch the semantics to the opposite of what they are now
without having an additional config value, but since that's not very
realistic given the migration effort required by users I think a flag would
probably be worth the costs I mentioned in my previous email although it's
definitely a trade-off. Some kinds of new user/existing survey would
probably help collect data to support a decision but could be tough to
conduct.
On Mon, Apr 15, 2019 at 4:34 PM James Meickle
<jmeic...@quantopian.com.invalid> wrote:
> Personally I would be very interested in working on a flexible schedule
> window/window projection patch. But it would be a big undertaking so it
> doesn't make sense to start it unless there's a lot of community buy-in to
> the idea that we aren't just for day-after ETL systems.
>
> On Mon, Apr 15, 2019 at 8:52 AM airflowuser
> <airflowu...@protonmail.com.invalid> wrote:
>
> > To quote my user-experience professor from ages ago:
> > "If too many people misuse something you wrote it means that YOU are
> doing
> > something wrong".
> >
> > Something can be well documented but if it's not intuitive it's likely
> > that people will get it wrong.
> >
> > Say someone ask "When did you execute the code?" Your answer will be
> > direct - the time the code started to run. This is why so many people
> > misunderstand the execution_date in the terms of Airflow. Airflow took a
> > word that is well defined in our conscious and replaced it's meaning.
> >
> >
> > ‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐
> > On Monday, April 15, 2019 3:35 PM, Dan Davydov
> > <ddavy...@twitter.com.INVALID> wrote:
> >
> > > I think if the mission of Airflow is to be a generic Workflow engine,
> the
> > > current semantics of execution date aren't a good default. This might
> be
> > an
> > > unpopular opinion given past threads on this topic :).
> > >
> > > The execution_date = end_date semantics make sense for the ETL use case
> > but
> > > not for other use cases I think Cron syntax is more intuitive to users,
> > > i.e. start_date should match execution_date (although I don't have data
> > to
> > > back this up). This is especially prevalent in ML, it's almost a rite
> of
> > > passage for users to get confused by execution date semantics. I think
> a
> > > flag to support different execution date semantics makes sense, even at
> > the
> > > cost of being a headache to support both and the complexity increase
> > could
> > > lead to bugs and trickier mailing list support.
> > >
> > > On Wed, Apr 10, 2019 at 9:00 PM Gabriel Silk gs...@dropbox.com.invalid
> > > wrote:
> > >
> > > > My two cents:
> > > > "execution_date" is definitely confusing to newcomers, and it's
> partly
> > the
> > > > ambiguity of the wording, and partly the UI's fault. When I first saw
> > > > execution date, I assumed it meant the earliest time at which the
> task
> > > > will execute, which is wrong. I was confused when no tasks appeared
> > for3pm until 4pm.
> > > > My proposal to fix that:
> > > >
> > > > 1. Always show the next task to be executed in the UI, but explain
> to
> > the
> > > > user that it's not running because its interval has not yet
> > completed.
> > > > Indicate this state visually, perhaps by using some transparency
> > or another
> > > > color.
> > > >
> > > > 2. Instead of just showing execution date in the UI, show the
> low/high
> > > > range of the time period it covers (for periodic jobs).
> > > >
> > > >
> > > > As for what we call the low/high timestamps, I like these two
> options:
> > > >
> > > > - low_ts, high_ts
> > > > - interval_start, interval_end
> > > >
> > > > On Wed, Apr 10, 2019 at 6:43 AM James Meickle
> > > > jmeic...@quantopian.com.invalid wrote:
> > > >
> > > > > Strictly tying execution start to interval end doesn't work for
> some
> > > > > workflows (my guess, 1-5% of them?):
> > > > >
> > > > > - You need to start performing tasks before the interval is over
> > > > > - You have tasks that reference a single interval, but can't be
> > completed
> > > > > until several intervals later (due to data latency)
> > > > >
> > > > > - The frequency you need to run the task on is different than the
> > > > > frequency
> > > > > of the interval you need to process (like processing all
> records
> > from the
> > > > > last five days, every day)
> > > > >
> > > > >
> > > > > Airflow doesn't handle any of these situations gracefully and I've
> > seen
> > > > > people attempt all sorts of workarounds for them. Probably even
> more
> > > > > people
> > > > > would try, if we provided decent idioms for doing it rather than
> > those
> > > > > workarounds.
> > > > > On Wed, Apr 10, 2019 at 9:30 AM Driesprong, Fokko
> > fo...@driesprong.frl
> > > > > wrote:
> > > > >
> > > > > > I see what you mean. I don't really like the `period_{start,end}`
> > name,
> > > > > > but
> > > > > > something such as `interval_{start,end}` might do it for me.
> > > > > > Personally, I think running the job after the interval closes
> > (since
> > > > > > then
> > > > >
> > > > > > you have all the data over the interval), makes complete sense
> for
> > ETL
> > > > > > jobs. I agree it requires some time to get used to. Maybe we're
> > lacking
> > > > > > on
> > > > > > documentation here.
> > > > > > Cheers, Fokko
> > > > > > Op wo 10 apr. 2019 om 10:08 schreef Flo Rance
> troura...@gmail.com:
> > > > > >
> > > > > > > I didn't expect to participate at any debate on that software,
> as
> > > > > > > I'm a
> > > > >
> > > > > > > complete newcomer. But I'm almost forced as I am the target
> > audience,
> > > > > > > too.
> > > > > > > To answer your initial question, after reading a lot of
> > > > > > > documentation I
> > > > >
> > > > > > > find the term execution_date really counterintuitive, so yes
> > maybe
> > > > > > > period_start and period_end might be a better naming to help to
> > > > > > > understand
> > > > > > > how all the initial scheduling works. Because even after
> reading
> > the
> > > > > > > scheduling section of the doc and the FAQ, it was still not
> > clear in
> > > > > > > my
> > > > >
> > > > > > > mind. Btw, I find some ideas exposed by James Meickle in the
> > > > > > > [DISCUSS]
> > > > >
> > > > > > > AIRFLOW-4192 very interesting and I share his opinion that
> > there's
> > > > > > > still
> > > > > >
> > > > > > > room for improvement.
> > > > > > > But a mode to change from "run at end of period, I need all the
> > data
> > > > > > > available for this period" (the current) to "run at this time
> on
> > > > > > > the
> > > > >
> > > > > > > schedule_interval would be awesome.
> > > > > > > Regards,
> > > > > > > Flo
> > > > > > > On Tue, Apr 9, 2019 at 4:41 PM Ash Berlin-Taylor
> a...@apache.org
> > > > > > > wrote:
> > > > > >
> > > > > > > > Yeah, that's the other thing that has been talked about from
> > > > > > > > time-to-time,
> > > > > > > > which is a mode to change from "run at end of period, I need
> > all
> > > > > > > > the
> > > > >
> > > > > > data
> > > > > >
> > > > > > > > available for this period" (the current) to "run at this time
> > on
> > > > > > > > the
> > > > > >
> > > > > > > > schedule_interval, don't wait for the period to end".
> > > > > > > > (No such flag exists right now, before you go looking.)
> > > > > > > >
> > > > > > > > > On 9 Apr 2019, at 15:31, Shaw, Damian P. <
> > > > > > > > > damian.sha...@credit-suisse.com> wrote:
> > > > > > > > > Hi all,
> > > > > > > > > I'm new to this Airflow Dev mailing list so I wasn't
> > expecting to
> > > > > > > > > reply
> > > > > > >
> > > > > > > > to anything but I feel I am the target audience for this
> > question.
> > > > > > > > I
> > > > > > > > am
> > > > >
> > > > > > > > quite new to airflow and have been setting up an airflow
> > > > > > > > environment
> > > > >
> > > > > > for
> > > > > >
> > > > > > > my
> > > > > > >
> > > > > > > > business this last month.
> > > > > > > >
> > > > > > > > > I find the current "execution_date" a small technical
> burden
> > and
> > > > > > > > > a
> > > > >
> > > > > > > large
> > > > > > >
> > > > > > > > cognitive burden. Our workflow is based on DAGs running at a
> > > > > > > > specified
> > > > > >
> > > > > > > time
> > > > > > >
> > > > > > > > in a specified timezone using the same date as the current
> > calendar
> > > > > > > > date.
> > > > > > >
> > > > > > > > > I have worked around this by creating my own macro and
> > context
> > > > > > > > > variables, with the logic looking like this:
> > > > > > > > > airflow_execution_date = context['execution_date']
> > > > > > > > > dag_timezone = context['dag'].timezone
> > > > > > > > > local_execution_date =
> > > > > > > > > dag_timezone.convert(airflow_execution_date)
> > > > > > > > > local_cal_date = local_execution_date +
> > > > > > > > > datetime.timedelta(days=1)
> > > > > > > >
> > > > > > > > > As you can see this isn't a lot of technical effort, but
> > having a
> > > > > > > > > date
> > > > > > >
> > > > > > > > that 1) is in the timezone the business users are working in,
> > and
> > > >
> > > > 2.
> > > >
> > > > > Is
> > > > >
> > > > > > > the
> > > > > > >
> > > > > > > > same calendar date the business users are working in it
> > > > > > > > significantly
> > > > >
> > > > > > > > reduces the cognitive effort required to set-up tasks. Of
> > course
> > > > > > > > this
> > > > >
> > > > > > > > doesn't help with cron format scheduling which I just let the
> > > > > > > > business
> > > > > >
> > > > > > > give
> > > > > > >
> > > > > > > > me the requirements for and I set it up myself as the date
> > logic
> > > > > > > > there
> > > > > > > > is
> > > > > >
> > > > > > > > still confusing as it doesn't work like real cron scheduling
> > which
> > > > > > > > everyone
> > > > > > > > is familiar with.
> > > > > > > >
> > > > > > > > > Maybe "period_start" and "period_end" might help people on
> > Day 0
> > > > > > > > > of
> > > > >
> > > > > > > > understanding Airflow get that the dates you are dealing with
> > are
> > > > > > > > not
> > > > >
> > > > > > > what
> > > > > > >
> > > > > > > > you expect, but Day 1+ there's still a lot of cognitive
> > overhead if
> > > > > > > > you
> > > > > >
> > > > > > > > don't have the exact same model as AirBnb for running DAGs
> and
> > > > > > > > tasks.
> > > > >
> > > > > > > > > My 2 cents anyway,
> > > > > > > > > Damian Shaw
> > > > > > > > > -----Original Message-----
> > > > > > > > > From: Ash Berlin-Taylor [mailto:a...@apache.org]
> > > > > > > > > Sent: Tuesday, April 09, 2019 10:08 AM
> > > > > > > > > To: dev@airflow.apache.org
> > > > > > > > > Subject: [DISCUSS] period_start/period_end instead of
> > > > > > > > > execution_date/next_execution_date
> > > > > > > > > (trying to break this out in to another thread)
> > > > > > > > > The ML doesn't allow images, but I can guess that it is the
> > deps
> > > > > > > > > section of a task instance details screen?
> > > > > > > > > I'm not saying it's not clear once you know to look there,
> > but
> > > > > > > > > I'm
> > > > >
> > > > > > > > trying remove/reduce the confusion in the first place. And I
> > think
> > > > > > > > we
> > > > >
> > > > > > as
> > > > > >
> > > > > > > > committers aren't best placed to know what makes sense as we
> > have
> > > > > > > > internalised how Airflow works :)
> > > > > > > >
> > > > > > > > > So I guess this is a question to the newest people on the
> > list:
> > > > > > > > > Would
> > > > > >
> > > > > > > > `period_start` and `period_end` be more or less confusing for
> > you
> > > > > > > > when
> > > > > >
> > > > > > > you
> > > > > > >
> > > > > > > > were first getting started with Airflow?
> > > > > > > >
> > > > > > > > > -ash
> > > > > > > > >
> > > > > > > > > > On 9 Apr 2019, at 14:47, Driesprong, Fokko
> > <fo...@driesprong.frl
> > > > >
> > > > > > > > wrote:
> > > > > > > >
> > > > > > > > > > Ash,
> > > > > > > > > > Personally, I think this is quite clear, there is a list
> of
> > > > > > > > > > reasons
> > > > > >
> > > > > > > why
> > > > > > >
> > > > > > > > the job isn't being scheduled:
> > > > > > > >
> > > > > > > > > > Coming back to the question of Bas, I believe that
> > yesterday_ds
> > > > > > > > > > does
> > > > > >
> > > > > > > > not make sense since we cannot assume that the schedule is
> > daily. I
> > > > > > > > don't
> > > > > > >
> > > > > > > > see any usage of this variable. Personally, I do use
> > > > > > > > next_execution_date
> > > > > > >
> > > > > > > > quite extensively. When you have a job that runs daily, but
> you
> > > > > > > > want
> > > > > > > > to
> > > > >
> > > > > > > > change this to an hourly job. In such a case you don't want
> to
> > > > > > > > change
> > > > >
> > > > > > {{
> > > > > >
> > > > > > > > (execution_date + macros.timedelta(days=1)) }} to {{
> > > > > > > > (execution_date
> > > > >
> > > > > -
> > > > >
> > > > > > > > macros.timedelta(hours=1)) }} everywhere.
> > > > > > > >
> > > > > > > > > > I'm just not sure if the aggressive deprecation of is
> > really
> > > > > > > > > > worth
> > > > >
> > > > > > it.
> > > > > >
> > > > > > > > I don't see too much harm in letting them stay.
> > > > > > > >
> > > > > > > > > > Cheers, Fokko
> > > > > > > > > > Op di 9 apr. 2019 om 12:17 schreef Ash Berlin-Taylor <
> > > > > > > > > > a...@apache.org
> > > > > > >
> > > > > > > > mailto:a...@apache.org>:
> > > > > > > >
> > > > > > > > > > To (slightly) hijack this thread:
> > > > > > > > > > On the subject of execuction_date: as I'm sure we're all
> > aware
> > > > > > > > > > the
> > > > >
> > > > > > > > concept of execution_date is confusing to new-commers to
> > Airflow
> > > > > > > > (there
> > > > > >
> > > > > > > are
> > > > > > >
> > > > > > > > many questions about "why hasn't my DAG run yet"? "Why is my
> > dag a
> > > > > > > > day
> > > > > >
> > > > > > > > behind?" etc.) and although we mention this in the docs it's
> a
> > > > > > > > confusing
> > > > > > >
> > > > > > > > concept.
> > > > > > > >
> > > > > > > > > > What to people think about adding two new parameters:
> > > > > > > > > > `period_start`
> > > > > >
> > > > > > > > and `period_end` and making these the preferred terms in
> place
> > of
> > > > > > > > execution_date and next_execution_date?
> > > > > > > >
> > > > > > > > > > This hopefully avoids any ambitious terms like
> "execution"
> > or
> > > > > > > > > > "run"
> > > > > >
> > > > > > > > which is understandably easy to conflate with the time the
> > task is
> > > > > > > > being
> > > > > > >
> > > > > > > > run (i.e. `now()`)
> > > > > > > >
> > > > > > > > > > If people think this naming is better and less confusing
> I
> > would
> > > > > > > > > > suggest we update all the docs and examples to use these
> > terms (but
> > > > > > > > > > still
> > > > > > >
> > > > > > > > mention the old names somewhere, probably in the macros docs)
> > > > > > > >
> > > > > > > > > > Thoughts?
> > > > > > > > > > -ash
> > > > > > > > > >
> > > > > > > > > > > On 8 Apr 2019, at 16:20, Arthur Wiedmer <
> > > > > > > > > > > arthur.wied...@gmail.com
> > > > > >
> > > > > > > > mailto:arthur.wied...@gmail.com> wrote:
> > > > > > > >
> > > > > > > > > > > Hi Bas,
> > > > > > > > > > >
> > > > > > > > > > > 1. I am aware of a few places where those parameters
> > are used
> > > > > > > > > > > in
> > > > > > > > > > >
> > > > >
> > > > > > > > production
> > > > > > > >
> > > > > > > > > > > in a few hundred jobs. I highly recommend we don't
> > deprecate
> > > > > > > > > > > them
> > > > >
> > > > > > > > unless we
> > > > > > > >
> > > > > > > > > > > do it in a major version.
> > > > > > > > > > >
> > > > > > > > > > > 2. As James mentioned, inlets and outlets are a
> lineage
> > > > > > > > > > > annotation
> > > > > > > > > > >
> > > > > >
> > > > > > > > feature
> > > > > > > >
> > > > > > > > > > > which is still under development. Let's leave them in,
> > but we
> > > > > > > > > > > can
> > > > >
> > > > > > > guard
> > > > > > >
> > > > > > > > > > > them behind a feature flag if you prefer.
> > > > > > > > > > >
> > > > > > > > > > > 3. the yesterday*/tomorrow* params are convenience
> ones
> > if you
> > > > > > > > > > > use
> > > > > > > > > > > a
> > > > > > > > > > >
> > > > > >
> > > > > > > > daily
> > > > > > > >
> > > > > > > > > > > ETL. I agree with you that they are simple to compute,
> > but not
> > > > > > > > > > > everyone
> > > > > > > >
> > > > > > > > > > > using Apache Airflow is amazing with Python. Some users
> > are
> > > > > > > > > > > only
> > > > >
> > > > > > > > trying to
> > > > > > > >
> > > > > > > > > > > get a query scheduled and rely on a couple of niceties
> > like
> > > > > > > > > > > these
> > > > >
> > > > > > to
> > > > > >
> > > > > > > > get by.
> > > > > > > >
> > > > > > > > > > > 4. latest_date, end_date (I feel like there used to be
> > > > > > > > > > > start_date,
> > > > > > > > > > >
> > > > > >
> > > > > > > but
> > > > > > >
> > > > > > > > > > > maybe it got lost) were a blend of things which were
> > used by a
> > > > > > > > > > > backfill
> > > > > > > >
> > > > > > > > > > > framework used internally at Airbnb. Latest date was
> > used if
> > > > > > > > > > > you
> > > > >
> > > > > > > > needed to
> > > > > > > >
> > > > > > > > > > > join to a dimension for which you only wanted the
> latest
> > > > > > > > > > > version
> > > > > > > > > > > of
> > > > >
> > > > > > > the
> > > > > > >
> > > > > > > > > > > attributes in you backfill. end_date was used for time
> > ranges
> > > > > > > > > > > where
> > > > > >
> > > > > > > > several
> > > > > > > >
> > > > > > > > > > > days were processed together in a range to save on
> > compute. I
> > > > > > > > > > > don't
> > > > > >
> > > > > > > > see an
> > > > > > > >
> > > > > > > > > > > issue with removing them.
> > > > > > > > > > > Best regards,
> > > > > > > > > > > Arthur
> > > > > > > > > > > On Mon, Apr 8, 2019 at 5:37 AM Bas Harenslak <
> > > > > > > > > > > basharens...@godatadriven.com <mailto:
> > > > > > > > > > > basharens...@godatadriven.com
> > > > >
> > > > > > > > > > > wrote:
> > > > > > > > > > >
> > > > > > > > > > > > Hi all,
> > > > > > > > > > > > Following Tao Feng’s question to discuss this PR<
> > > > > > > > > > > > https://github.com/apache/airflow/pull/5010 <
> > > > > > > > > > > > https://github.com/apache/airflow/pull/5010>>
> > (AIRFLOW-4192<
> > > > > > > > >
> > > > > > > > > > > > https://issues.apache.org/jira/browse/AIRFLOW-4192 <
> > > > > > > > > > > > https://issues.apache.org/jira/browse/AIRFLOW-4192
> >>),
> > please
> > > > > > > > > > > > discuss
> > > > > >
> > > > > > > here
> > > > > > >
> > > > > > > > > > > > if you agree/disagree/would change.
> > > > > > > > > > > >
> > > > > > > > > > > > The summary of the PR:
> > > > > > > > > > > > I was confused by the task context values and suggest
> > to clean
> > > > > > > > > > > > up
> > > > > >
> > > > > > > and
> > > > > > >
> > > > > > > > > > > > clarify these variables. Some are derivations from
> > other
> > > > > > > > > > > > variables,
> > > > > > >
> > > > > > > > some
> > > > > > > >
> > > > > > > > > > > > are undocumented and unused, some are wrong (name
> > doesn’t
> > > > > > > > > > > > match
> > > > >
> > > > > > the
> > > > > >
> > > > > > > > value).
> > > > > > > >
> > > > > > > > > > > > Please discuss what you think of the removal of these
> > > > > > > > > > > > variables:
> > > > >
> > > > > > > > > > > > - Removed yesterday_ds, yesterday_ds_nodash,
> > tomorrow_ds,
> > > > > > > > > > > > tomorrow_ds_nodash. IMO the next_* and previous_*
> > variables
> > > > > > > > > > > > are
> > > > > > > > > > > >
> > > > >
> > > > > > > useful
> > > > > > >
> > > > > > > > > > > > since these require complex logic to compute the next
> > > > > > > > > > > > execution
> > > > >
> > > > > > > date,
> > > > > > >
> > > > > > > > > > > > however would leave computing the yesterday* and
> > tomorrow*
> > > > > > > > > > > > variables
> > > > > > >
> > > > > > > > up to
> > > > > > > >
> > > > > > > > > > > > the user since they are simple one-liners and don't
> > relate to
> > > > > > > > > > > > the
> > > > > >
> > > > > > > DAG
> > > > > > >
> > > > > > > > > > > > interval.
> > > > > > > > > > > >
> > > > > > > > > > > > - Removed tables. This is a field in params, and is
> > thus
> > > > > > > > > > > > also
> > > > > > > > > > > >
> > > > >
> > > > > > > > > > > > accessible by the user ({{ params.tables }}). Also,
> it
> > was
> > > > > > > > > > > > undocumented.
> > > > > > > > >
> > > > > > > > > > > > - Removed latest_date. It's the same as ds and was
> > also
> > > > > > > > > > > > undocumented.
> > > > > > > > > > > >
> > > > > > > > >
> > > > > > > > > > > > - Removed inlets and outlets. Also undocumented,
> and
> > have
> > > > > > > > > > > > the
> > > > > > > > > > > >
> > > > >
> > > > > > > > > > > > inlets/outlets ever worked/ever been used by anybody?
> > > > > > > > > > > >
> > > > > > > > > > > > - Removed end_date and END_DATE. Both have the same
> > value,
> > > > > > > > > > > > so
> > > > > > > > > > > > it
> > > > > > > > > > > >
> > > > >
> > > > > > > > > > > > doesn't make sense to have both variables. Also, the
> > value is
> > > > > > > > > > > > ds
> > > > >
> > > > > > > which
> > > > > > >
> > > > > > > > > > > > contains the start date of the interval, so the
> naming
> > didn't
> > > > > > > > > > > > make
> > > > > >
> > > > > > > > sense to
> > > > > > > >
> > > > > > > > > > > > me. However, if anybody argues in favour of adding
> > > > > > > > > > > > "start_date"
> > > > >
> > > > > > and
> > > > > >
> > > > > > > > > > > > "end_date" to provide the start and end datetime of
> > task
> > > > > > > > > > > > instance
> > > > > >
> > > > > > > > > > > > intervals, I'd be happy to add them.
> > > > > > > > > > > > Cheers,
> > > > > > > > > > > > Bas
> > > >
> > > >
> >
> ===============================================================================
> > > >
> > > > > > > > > Please access the attached hyperlink for an important
> > electronic
> > > > > > > > > communications disclaimer:
> > > > > > > > >
> > http://www.credit-suisse.com/legal/en/disclaimer_email_ib.html
> > > >
> > > >
> >
> ===============================================================================
> > > >
> > > > > > > >
> >
> >
> >
>
