To clarify it isn't required to have the initializer in the first cogroup
because the first aggregator will have the value type. I like how the
initializer makes it abundantly clear that the final type will be that.
Right now I'm split because the case may be made that you want to supply a
different initializer to different aggregate calls, but like I said it
makes it clear to the user what their final value is going to be.
On Jun 14, 2017 4:23 PM, "Guozhang Wang" <wangg...@gmail.com> wrote:
> I'd suggest we do not block this KIP until the serde work has been sorted
> out: we cannot estimate yet how long it will take yet. Instead let's say
> make an agreement on where we want to specify the serdes: whether on the
> first co-group call or on the aggregate call.
>
> Also about the initializer specification I actually felt that the first
> cogrouped stream is special (Kyle please feel free to correct me if I'm
> wrong) and that is why I thought it is better to specify the initializer at
> the beginning: since from the typing you can see that the final aggregated
> value type is defined to be the same as the first co-grouped stream, and
> for any intermediate stream to co-group, their value types not be inherited
> but the value be "incorporated" into the original stream:
>
> <T> CogroupedKStream<K, V> cogroup(final KGroupedStream<K, T>
> groupedStream, final Aggregator<? super K, ? super T, V> aggregator)
>
> Note that we do not have a cogroup function that returns
> CogroupedKStream<K, T>.
>
>
> Guozhang
>
>
> On Tue, Jun 13, 2017 at 2:31 PM, Bill Bejeck <bbej...@gmail.com> wrote:
>
> > +1 on deferring discussion on Serdes until API improvements are ironed
> out.
> >
> > On Tue, Jun 13, 2017 at 2:06 PM, Matthias J. Sax <matth...@confluent.io>
> > wrote:
> >
> > > Hi,
> > >
> > > I am just catching up on this thread. (1) as most people agree, we
> > > should not add anything to KStreamBuilder (btw: we actually plan to
> move
> > > #merge() to KStream and deprecate it on KStreamBuilder as it's a quite
> > > unnatural API atm).
> > >
> > > About specifying Serdes: there is still the idea to improve to overall
> > > API from the current "we are adding more overloads"-pattern to a
> > > builder-like pattern. This might make the whole discussion void if we
> do
> > > this. Thus, it might make sense to keep this in mind (or even delay
> this
> > > KIP?). It seems a waste of time to discuss all this if we are going to
> > > chance it in 2 month anyway... Just saying.
> > >
> > >
> > > -Matthias
> > >
> > > On 6/13/17 8:05 AM, Michal Borowiecki wrote:
> > > > You're right, I haven't thought of that.
> > > >
> > > > Cheers,
> > > >
> > > > Michał
> > > >
> > > >
> > > > On 13/06/17 13:00, Kyle Winkelman wrote:
> > > >> First, I would prefer not calling it aggregate because there are
> > already
> > > >> plenty of aggregate methods.
> > > >>
> > > >> Second, I dont think this would really work because after each
> > aggregate
> > > >> you now have a unique KTable (someone may want a table with 4
> streams
> > > and
> > > >> reuse those 4 in another table but with one more stream added) and
> > > unless
> > > >> we completely duplicate everything every time this isnt really
> > possible.
> > > >> Additionally, the cogroup way just requires 1 more call to create
> two
> > > >> different tables (normal, windowed, and session windowed) this new
> way
> > > >> would require copying the aggregate chain.
> > > >>
> > > >> Another way to think about it is with cogroup we know that when they
> > > call
> > > >> aggregate they arent going to be adding any more aggregators to that
> > > table
> > > >> but your way requires us to assume they are done adding aggregators
> > > after
> > > >> each call so we must return a ktable just to possibly not need to
> have
> > > >> created it.
> > > >>
> > > >> On Jun 13, 2017 5:20 AM, "Michal Borowiecki" <
> > > michal.borowie...@openbet.com>
> > > >> wrote:
> > > >>
> > > >>> Actually, just had a thought. It started with naming.
> > > >>>
> > > >>> Are we actually co-grouping these streams or are we co-aggregating
> > > them?
> > > >>>
> > > >>> After all, in each of the cogroup calls we are providing an
> > Aggregator
> > > >>> implementation.
> > > >>>
> > > >>>
> > > >>> If they are really co-aggregated, why don't we turn this around:
> > > >>> KGroupedStream<K, V1> grouped1 = builder.stream("topic1").
> > > groupByKey();
> > > >>> KGroupedStream<K, V2> grouped2 = builder.stream("topic2").
> > > groupByKey();
> > > >>> KGroupedStream<K, V3> grouped3 = builder.stream("topic3").
> > > groupByKey();
> > > >>>
> > > >>> KTable<K, CG> coagg = grouped1.aggregate(initializer1,
> aggregator1,
> > > >>> aggValueSerde1) // this is the unchanged aggregate method
> > > >>> .aggregate(grouped2, aggregator2) // this is a new method
> > > >>> .aggregate(grouped3, aggregator3); // ditto
> > > >>>
> > > >>> This means instead of adding cogroup methods on KGroupStream
> > interface,
> > > >>> adding aggregate method on KTable interface.
> > > >>>
> > > >>> Is that feasible?
> > > >>>
> > > >>> Cheers,
> > > >>> Michał
> > > >>>
> > > >>> On 13/06/17 10:56, Michal Borowiecki wrote:
> > > >>>
> > > >>> Also, I still feel that putting initializer on the first cogroup
> can
> > > >>> mislead users into thinking the first stream is in some way
> special.
> > > >>> Just my 5c.
> > > >>> Michał
> > > >>>
> > > >>> On 13/06/17 09:54, Michal Borowiecki wrote:
> > > >>>
> > > >>> Agree completely with the argument for serdes belonging in the same
> > > place
> > > >>> as the state store name, which is in the aggregate method.
> > > >>>
> > > >>> Cheers,
> > > >>>
> > > >>> Michał
> > > >>>
> > > >>> On 12/06/17 18:20, Xavier Léauté wrote:
> > > >>>
> > > >>> I think we are discussing two separate things here, so it might be
> > > worth
> > > >>> clarifying:
> > > >>>
> > > >>> 1) the position of the initializer with respect to the aggregators.
> > If
> > > I
> > > >>> understand correctly, Guozhang seems to think it is more natural to
> > > specify
> > > >>> the initializer first, despite it not bearing any relation to the
> > first
> > > >>> aggregator. I can see the argument for specifying the initializer
> > > first,
> > > >>> but I think it is debatable whether mixing it into the first
> cogroup
> > > call
> > > >>> leads to a cleaner API or not.
> > > >>>
> > > >>> 2) where the serde should be defined (if necessary). Looking at our
> > > >>> existing APIs in KGroupedStreams, we always offer two aggregate()
> > > >>> methods. The first one takes the name of the store and associated
> > > aggregate
> > > >>> value serde e.g. KGroupedStream.aggregate(Initializer<VR>
> > initializer,
> > > >>> Aggregator<? super K, ? super V, VR> aggregator, Serde<VR>
> > > aggValueSerde,
> > > >>> String queryableStoreName)
> > > >>> The second one only takes a state store supplier, and does not
> > specify
> > > any
> > > >>> serde, e.g. KGroupedStream.aggregate(Initializer<VR>
> > > >>> initializer, Aggregator<? super K, ? super V, VR> aggregator, final
> > > >>> StateStoreSupplier<KeyValueStore> storeSupplier)
> > > >>> Presumably, when specifying a state store supplier it shouldn't be
> > > >>> necessary to specify an aggregate value serde, since the provided
> > > >>> statestore might not need to serialize the values (e.g. it may just
> > > keep
> > > >>> them as regular objects in heap) or it may have its own
> > > >>> internal serialization format.
> > > >>>
> > > >>> For consistency I think it would be valuable to preserve the same
> two
> > > >>> aggregate methods for cogroup as well. Since the serde is only
> > > required in
> > > >>> one of the two cases, I believe the serde has no place in the first
> > > >>> cogroup() call and should only have to be specified as part of the
> > > >>> aggregate() method that takes a state store name. In the case of a
> > > state
> > > >>> store supplier, no serde would be necessary.
> > > >>>
> > > >>>
> > > >>> On Sat, Jun 10, 2017 at 4:09 PM Guozhang Wang <wangg...@gmail.com>
> > > wrote:
> > > >>>
> > > >>>> I'd agree that the aggregate value serde and the initializer does
> > not
> > > >>>> bear direct relationship with the first `cogroup` calls, but
> after I
> > > tried
> > > >>>> to write some example code with these two different set of APIs I
> > > felt the
> > > >>>> current APIs just program more naturally.
> > > >>>>
> > > >>>> I know it is kinda subjective, but I do think that user experience
> > > may be
> > > >>>> more important as a deciding factor than the logical argument for
> > > public
> > > >>>> interfaces. So I'd recommend people to also try out writing some
> > > example
> > > >>>> lines also and we can circle back and discuss which one feels more
> > > natural
> > > >>>> to write code.
> > > >>>>
> > > >>>>
> > > >>>> Guozhang
> > > >>>>
> > > >>>> On Fri, Jun 9, 2017 at 1:59 AM, Michal Borowiecki <
> > > >>>> michal.borowie...@openbet.com> wrote:
> > > >>>>
> > > >>>>> I feel it would make more sense to move the initializer and serde
> > to
> > > the
> > > >>>>> final aggregate statement, since the serde only applies to the
> > state
> > > >>>>> store,
> > > >>>>> and the initializer doesn't bear any relation to the first group
> in
> > > >>>>> particular.
> > > >>>>>
> > > >>>>> +1 for moving initializer and serde from cogroup() to the
> > aggregate()
> > > >>>>> for the reasons mentioned above.
> > > >>>>>
> > > >>>>> Cheers,
> > > >>>>>
> > > >>>>> Michał
> > > >>>>>
> > > >>>>> On 08/06/17 22:44, Guozhang Wang wrote:
> > > >>>>>
> > > >>>> Note that although the internal `AbstractStoreSupplier` does
> > maintain
> > > the
> > > >>>>> key-value serdes, we do not enforce the interface of
> > > `StateStoreSupplier`
> > > >>>>> to always retain that information, and hence we cannot assume
> that
> > > >>>>> StateStoreSuppliers always retain key / value serdes.
> > > >>>>>
> > > >>>>> On Thu, Jun 8, 2017 at 11:51 AM, Xavier Léauté <
> > xav...@confluent.io>
> > > <xav...@confluent.io> wrote:
> > > >>>>>
> > > >>>>>
> > > >>>>> Another reason for the serde not to be in the first cogroup call,
> > is
> > > that
> > > >>>>> the serde should not be required if you pass a StateStoreSupplier
> > to
> > > >>>>> aggregate()
> > > >>>>>
> > > >>>>> Regarding the aggregated type <T> I don't the why initializer
> > should
> > > be
> > > >>>>> favored over aggregator to define the type. In my mind separating
> > the
> > > >>>>> initializer into the last aggregate call clearly indicates that
> the
> > > >>>>> initializer is independent of any of the aggregators or streams
> and
> > > that we
> > > >>>>> don't wait for grouped1 events to initialize the co-group.
> > > >>>>>
> > > >>>>> On Thu, Jun 8, 2017 at 11:14 AM Guozhang Wang <
> wangg...@gmail.com>
> > <
> > > wangg...@gmail.com> wrote:
> > > >>>>>
> > > >>>>>
> > > >>>>> On a second thought... This is the current proposal API
> > > >>>>>
> > > >>>>>
> > > >>>>> ```
> > > >>>>>
> > > >>>>> <T> CogroupedKStream<K, T> cogroup(final Initializer<T>
> > initializer,
> > > >>>>>
> > > >>>>> final
> > > >>>>>
> > > >>>>> Aggregator<? super K, ? super V, T> aggregator, final Serde<T>
> > > >>>>> aggValueSerde)
> > > >>>>>
> > > >>>>> ```
> > > >>>>>
> > > >>>>>
> > > >>>>> If we do not have the initializer in the first co-group it might
> be
> > > a bit
> > > >>>>> awkward for users to specify the aggregator that returns a typed
> > <T>
> > > >>>>>
> > > >>>>> value?
> > > >>>>>
> > > >>>>> Maybe it is still better to put these two functions in the same
> > api?
> > > >>>>>
> > > >>>>>
> > > >>>>>
> > > >>>>> Guozhang
> > > >>>>>
> > > >>>>> On Thu, Jun 8, 2017 at 11:08 AM, Guozhang Wang <
> wangg...@gmail.com
> > >
> > > <wangg...@gmail.com>
> > > >>>>>
> > > >>>>> wrote:
> > > >>>>>
> > > >>>>> This suggestion lgtm. I would vote for the first alternative than
> > > >>>>>
> > > >>>>> adding
> > > >>>>>
> > > >>>>> it to the `KStreamBuilder` though.
> > > >>>>>
> > > >>>>> On Thu, Jun 8, 2017 at 10:58 AM, Xavier Léauté <
> > xav...@confluent.io>
> > > <xav...@confluent.io>
> > > >>>>> wrote:
> > > >>>>>
> > > >>>>>
> > > >>>>> I have a minor suggestion to make the API a little bit more
> > > symmetric.
> > > >>>>> I feel it would make more sense to move the initializer and serde
> > to
> > > >>>>>
> > > >>>>> the
> > > >>>>>
> > > >>>>> final aggregate statement, since the serde only applies to the
> > state
> > > >>>>> store,
> > > >>>>> and the initializer doesn't bear any relation to the first group
> in
> > > >>>>> particular. It would end up looking like this:
> > > >>>>>
> > > >>>>> KTable<K, CG> cogrouped =
> > > >>>>> grouped1.cogroup(aggregator1)
> > > >>>>> .cogroup(grouped2, aggregator2)
> > > >>>>> .cogroup(grouped3, aggregator3)
> > > >>>>> .aggregate(initializer1, aggValueSerde, storeName1);
> > > >>>>>
> > > >>>>> Alternatively, we could move the the first cogroup() method to
> > > >>>>> KStreamBuilder, similar to how we have .merge()
> > > >>>>> and end up with an api that would be even more symmetric.
> > > >>>>>
> > > >>>>> KStreamBuilder.cogroup(grouped1, aggregator1)
> > > >>>>> .cogroup(grouped2, aggregator2)
> > > >>>>> .cogroup(grouped3, aggregator3)
> > > >>>>> .aggregate(initializer1, aggValueSerde,
> storeName1);
> > > >>>>>
> > > >>>>> This doesn't have to be a blocker, but I thought it would make
> the
> > > API
> > > >>>>> just
> > > >>>>> a tad cleaner.
> > > >>>>>
> > > >>>>> On Tue, Jun 6, 2017 at 3:59 PM Guozhang Wang <wangg...@gmail.com
> >
> > <
> > > wangg...@gmail.com>
> > > >>>>>
> > > >>>>> wrote:
> > > >>>>>
> > > >>>>> Kyle,
> > > >>>>>
> > > >>>>> Thanks a lot for the updated KIP. It looks good to me.
> > > >>>>>
> > > >>>>>
> > > >>>>> Guozhang
> > > >>>>>
> > > >>>>>
> > > >>>>> On Fri, Jun 2, 2017 at 5:37 AM, Jim Jagielski <j...@jagunet.com>
> <
> > > j...@jagunet.com>
> > > >>>>>
> > > >>>>> wrote:
> > > >>>>>
> > > >>>>> This makes much more sense to me. +1
> > > >>>>>
> > > >>>>>
> > > >>>>> On Jun 1, 2017, at 10:33 AM, Kyle Winkelman <
> > > >>>>>
> > > >>>>> winkelman.k...@gmail.com>
> > > >>>>>
> > > >>>>> wrote:
> > > >>>>>
> > > >>>>> I have updated the KIP and my PR. Let me know what you think.
> > > >>>>> To created a cogrouped stream just call cogroup on a
> > > >>>>>
> > > >>>>> KgroupedStream
> > > >>>>>
> > > >>>>> and
> > > >>>>>
> > > >>>>> supply the initializer, aggValueSerde, and an aggregator. Then
> > > >>>>>
> > > >>>>> continue
> > > >>>>>
> > > >>>>> adding kgroupedstreams and aggregators. Then call one of the
> > > >>>>>
> > > >>>>> many
> > > >>>>>
> > > >>>>> aggregate
> > > >>>>>
> > > >>>>> calls to create a KTable.
> > > >>>>>
> > > >>>>> Thanks,
> > > >>>>> Kyle
> > > >>>>>
> > > >>>>> On Jun 1, 2017 4:03 AM, "Damian Guy" <damian....@gmail.com> <
> > > damian....@gmail.com>
> > > >>>>>
> > > >>>>> wrote:
> > > >>>>>
> > > >>>>> Hi Kyle,
> > > >>>>>
> > > >>>>> Thanks for the update. I think just one initializer makes sense
> > > >>>>>
> > > >>>>> as
> > > >>>>>
> > > >>>>> it
> > > >>>>>
> > > >>>>> should only be called once per key and generally it is just
> > > >>>>>
> > > >>>>> going
> > > >>>>>
> > > >>>>> to
> > > >>>>>
> > > >>>>> create
> > > >>>>>
> > > >>>>> a new instance of whatever the Aggregate class is.
> > > >>>>>
> > > >>>>> Cheers,
> > > >>>>> Damian
> > > >>>>>
> > > >>>>> On Wed, 31 May 2017 at 20:09 Kyle Winkelman <
> > > >>>>>
> > > >>>>> winkelman.k...@gmail.com
> > > >>>>>
> > > >>>>> wrote:
> > > >>>>>
> > > >>>>>
> > > >>>>> Hello all,
> > > >>>>>
> > > >>>>> I have spent some more time on this and the best alternative I
> > > >>>>>
> > > >>>>> have
> > > >>>>>
> > > >>>>> come
> > > >>>>>
> > > >>>>> up
> > > >>>>>
> > > >>>>> with is:
> > > >>>>> KGroupedStream has a single cogroup call that takes an
> > > >>>>>
> > > >>>>> initializer
> > > >>>>>
> > > >>>>> and
> > > >>>>>
> > > >>>>> an
> > > >>>>>
> > > >>>>> aggregator.
> > > >>>>> CogroupedKStream has a cogroup call that takes additional
> > > >>>>>
> > > >>>>> groupedStream
> > > >>>>>
> > > >>>>> aggregator pairs.
> > > >>>>> CogroupedKStream has multiple aggregate methods that create
> > > >>>>>
> > > >>>>> the
> > > >>>>>
> > > >>>>> different
> > > >>>>>
> > > >>>>> stores.
> > > >>>>>
> > > >>>>> I plan on updating the kip but I want people's input on if we
> > > >>>>>
> > > >>>>> should
> > > >>>>>
> > > >>>>> have
> > > >>>>>
> > > >>>>> the initializer be passed in once at the beginning or if we
> > > >>>>>
> > > >>>>> should
> > > >>>>>
> > > >>>>> instead
> > > >>>>>
> > > >>>>> have the initializer be required for each call to one of the
> > > >>>>>
> > > >>>>> aggregate
> > > >>>>>
> > > >>>>> calls. The first makes more sense to me but doesnt allow the
> > > >>>>>
> > > >>>>> user
> > > >>>>>
> > > >>>>> to
> > > >>>>>
> > > >>>>> specify different initializers for different tables.
> > > >>>>>
> > > >>>>> Thanks,
> > > >>>>> Kyle
> > > >>>>>
> > > >>>>> On May 24, 2017 7:46 PM, "Kyle Winkelman" <
> > > >>>>>
> > > >>>>> winkelman.k...@gmail.com>
> > > >>>>>
> > > >>>>> wrote:
> > > >>>>>
> > > >>>>>
> > > >>>>> Yea I really like that idea I'll see what I can do to update
> > > >>>>>
> > > >>>>> the
> > > >>>>>
> > > >>>>> kip
> > > >>>>>
> > > >>>>> and
> > > >>>>>
> > > >>>>> my pr when I have some time. I'm not sure how well creating
> > > >>>>>
> > > >>>>> the
> > > >>>>>
> > > >>>>> kstreamaggregates will go though because at that point I will
> > > >>>>>
> > > >>>>> have
> > > >>>>>
> > > >>>>> thrown
> > > >>>>>
> > > >>>>> away the type of the values. It will be type safe I just may
> > > >>>>>
> > > >>>>> need to
> > > >>>>>
> > > >>>>> do a
> > > >>>>>
> > > >>>>> little forcing.
> > > >>>>>
> > > >>>>> Thanks,
> > > >>>>> Kyle
> > > >>>>>
> > > >>>>> On May 24, 2017 3:28 PM, "Guozhang Wang" <wangg...@gmail.com
> > > >>>>>
> > > >>>>> wrote:
> > > >>>>>
> > > >>>>> Kyle,
> > > >>>>>
> > > >>>>> Thanks for the explanations, my previous read on the wiki
> > > >>>>>
> > > >>>>> examples
> > > >>>>>
> > > >>>>> was
> > > >>>>>
> > > >>>>> wrong.
> > > >>>>>
> > > >>>>> So I guess my motivation should be "reduced" to: can we move
> > > >>>>>
> > > >>>>> the
> > > >>>>>
> > > >>>>> window
> > > >>>>>
> > > >>>>> specs param from "KGroupedStream#cogroup(..)" to
> > > >>>>> "CogroupedKStream#aggregate(..)", and my motivations are:
> > > >>>>>
> > > >>>>> 1. minor: we can reduce the #.generics in CogroupedKStream
> > > >>>>>
> > > >>>>> from
> > > >>>>>
> > > >>>>> 3
> > > >>>>>
> > > >>>>> to
> > > >>>>>
> > > >>>>> 2.
> > > >>>>>
> > > >>>>> 2. major: this is for extensibility of the APIs, and since
> > > >>>>>
> > > >>>>> we
> > > >>>>>
> > > >>>>> are
> > > >>>>>
> > > >>>>> removing
> > > >>>>>
> > > >>>>> the "Evolving" annotations on Streams it may be harder to
> > > >>>>>
> > > >>>>> change it
> > > >>>>>
> > > >>>>> again
> > > >>>>>
> > > >>>>> in the future. The extended use cases are that people wanted
> > > >>>>>
> > > >>>>> to
> > > >>>>>
> > > >>>>> have
> > > >>>>>
> > > >>>>> windowed running aggregates on different granularities, e.g.
> > > >>>>>
> > > >>>>> "give
> > > >>>>>
> > > >>>>> me
> > > >>>>>
> > > >>>>> the
> > > >>>>>
> > > >>>>> counts per-minute, per-hour, per-day and per-week", and
> > > >>>>>
> > > >>>>> today
> > > >>>>>
> > > >>>>> in
> > > >>>>>
> > > >>>>> DSL
> > > >>>>>
> > > >>>>> we
> > > >>>>>
> > > >>>>> need to specify that case in multiple aggregate operators,
> > > >>>>>
> > > >>>>> which
> > > >>>>>
> > > >>>>> gets
> > > >>>>>
> > > >>>>> a
> > > >>>>>
> > > >>>>> state store / changelog, etc. And it is possible to optimize
> > > >>>>>
> > > >>>>> it
> > > >>>>>
> > > >>>>> as
> > > >>>>>
> > > >>>>> well
> > > >>>>>
> > > >>>>> to
> > > >>>>>
> > > >>>>> a single state store. Its implementation would be tricky as
> > > >>>>>
> > > >>>>> you
> > > >>>>>
> > > >>>>> need
> > > >>>>>
> > > >>>>> to
> > > >>>>>
> > > >>>>> contain different lengthed windows within your window store
> > > >>>>>
> > > >>>>> but
> > > >>>>>
> > > >>>>> just
> > > >>>>>
> > > >>>>> from
> > > >>>>>
> > > >>>>> the public API point of view, it could be specified as:
> > > >>>>>
> > > >>>>> CogroupedKStream stream = stream1.cogroup(stream2, ...
> > > >>>>> "state-store-name");
> > > >>>>>
> > > >>>>> table1 = stream.aggregate(/*per-minute window*/)
> > > >>>>> table2 = stream.aggregate(/*per-hour window*/)
> > > >>>>> table3 = stream.aggregate(/*per-day window*/)
> > > >>>>>
> > > >>>>> while underlying we are only using a single store
> > > >>>>>
> > > >>>>> "state-store-name"
> > > >>>>>
> > > >>>>> for
> > > >>>>>
> > > >>>>> it.
> > > >>>>>
> > > >>>>>
> > > >>>>> Although this feature is out of the scope of this KIP, I'd
> > > >>>>>
> > > >>>>> like
> > > >>>>>
> > > >>>>> to
> > > >>>>>
> > > >>>>> discuss
> > > >>>>>
> > > >>>>> if we can "leave the door open" to make such changes without
> > > >>>>>
> > > >>>>> modifying
> > > >>>>>
> > > >>>>> the
> > > >>>>>
> > > >>>>> public APIs .
> > > >>>>>
> > > >>>>> Guozhang
> > > >>>>>
> > > >>>>>
> > > >>>>> On Wed, May 24, 2017 at 3:57 AM, Kyle Winkelman <
> > > >>>>>
> > > >>>>> winkelman.k...@gmail.com
> > > >>>>>
> > > >>>>> wrote:
> > > >>>>>
> > > >>>>>
> > > >>>>> I allow defining a single window/sessionwindow one time
> > > >>>>>
> > > >>>>> when
> > > >>>>>
> > > >>>>> you
> > > >>>>>
> > > >>>>> make
> > > >>>>>
> > > >>>>> the
> > > >>>>>
> > > >>>>> cogroup call from a KGroupedStream. From then on you are
> > > >>>>>
> > > >>>>> using
> > > >>>>>
> > > >>>>> the
> > > >>>>>
> > > >>>>> cogroup
> > > >>>>>
> > > >>>>> call from with in CogroupedKStream which doesnt accept any
> > > >>>>>
> > > >>>>> additional
> > > >>>>>
> > > >>>>> windows/sessionwindows.
> > > >>>>>
> > > >>>>> Is this what you meant by your question or did I
> > > >>>>>
> > > >>>>> misunderstand?
> > > >>>>>
> > > >>>>> On May 23, 2017 9:33 PM, "Guozhang Wang" <
> > > >>>>>
> > > >>>>> wangg...@gmail.com
> > > >>>>>
> > > >>>>> wrote:
> > > >>>>>
> > > >>>>> Another question that came to me is on "window alignment":
> > > >>>>>
> > > >>>>> from
> > > >>>>>
> > > >>>>> the
> > > >>>>>
> > > >>>>> KIP
> > > >>>>>
> > > >>>>> it
> > > >>>>>
> > > >>>>> seems you are allowing users to specify a (potentially
> > > >>>>>
> > > >>>>> different)
> > > >>>>>
> > > >>>>> window
> > > >>>>>
> > > >>>>> spec in each co-grouped input stream. So if these window
> > > >>>>>
> > > >>>>> specs
> > > >>>>>
> > > >>>>> are
> > > >>>>>
> > > >>>>> different how should we "align" them with different input
> > > >>>>>
> > > >>>>> streams? I
> > > >>>>>
> > > >>>>> think
> > > >>>>>
> > > >>>>> it is more natural to only specify on window spec in the
> > > >>>>>
> > > >>>>> KTable<RK, V> CogroupedKStream#aggregate(Windows);
> > > >>>>>
> > > >>>>>
> > > >>>>> And remove it from the cogroup() functions. WDYT?
> > > >>>>>
> > > >>>>>
> > > >>>>> Guozhang
> > > >>>>>
> > > >>>>> On Tue, May 23, 2017 at 6:22 PM, Guozhang Wang <
> > > >>>>>
> > > >>>>> wangg...@gmail.com>
> > > >>>>>
> > > >>>>> wrote:
> > > >>>>>
> > > >>>>> Thanks for the proposal Kyle, this is a quite common use
> > > >>>>>
> > > >>>>> case
> > > >>>>>
> > > >>>>> to
> > > >>>>>
> > > >>>>> support
> > > >>>>>
> > > >>>>> such multi-way table join (i.e. N source tables with N
> > > >>>>>
> > > >>>>> aggregate
> > > >>>>>
> > > >>>>> func)
> > > >>>>>
> > > >>>>> with
> > > >>>>>
> > > >>>>> a single store and N+1 serdes, I have seen lots of people
> > > >>>>>
> > > >>>>> using
> > > >>>>>
> > > >>>>> the
> > > >>>>>
> > > >>>>> low-level PAPI to achieve this goal.
> > > >>>>>
> > > >>>>>
> > > >>>>> On Fri, May 19, 2017 at 10:04 AM, Kyle Winkelman <
> > > >>>>>
> > > >>>>> winkelman.k...@gmail.com
> > > >>>>>
> > > >>>>> wrote:
> > > >>>>>
> > > >>>>> I like your point about not handling other cases such as
> > > >>>>>
> > > >>>>> count
> > > >>>>>
> > > >>>>> and
> > > >>>>>
> > > >>>>> reduce.
> > > >>>>>
> > > >>>>> I think that reduce may not make sense because reduce
> > > >>>>>
> > > >>>>> assumes
> > > >>>>>
> > > >>>>> that
> > > >>>>>
> > > >>>>> the
> > > >>>>>
> > > >>>>> input values are the same as the output values. With
> > > >>>>>
> > > >>>>> cogroup
> > > >>>>>
> > > >>>>> ...
> > > >
> > > > --
> > > > Signature
> > > > <http://www.openbet.com/> Michal Borowiecki
> > > > Senior Software Engineer L4
> > > > T: +44 208 742 1600
> > > >
> > > >
> > > > +44 203 249 8448
> > > >
> > > >
> > > >
> > > > E: michal.borowie...@openbet.com
> > > > W: www.openbet.com <http://www.openbet.com/>
> > > >
> > > >
> > > > OpenBet Ltd
> > > >
> > > > Chiswick Park Building 9
> > > >
> > > > 566 Chiswick High Rd
> > > >
> > > > London
> > > >
> > > > W4 5XT
> > > >
> > > > UK
> > > >
> > > >
> > > > <https://www.openbet.com/email_promo>
> > > >
> > > > This message is confidential and intended only for the addressee. If
> > you
> > > > have received this message in error, please immediately notify the
> > > > postmas...@openbet.com <mailto:postmas...@openbet.com> and delete it
> > > > from your system as well as any copies. The content of e-mails as
> well
> > > > as traffic data may be monitored by OpenBet for employment and
> security
> > > > purposes. To protect the environment please do not print this e-mail
> > > > unless necessary. OpenBet Ltd. Registered Office: Chiswick Park
> > Building
> > > > 9, 566 Chiswick High Road, London, W4 5XT, United Kingdom. A company
> > > > registered in England and Wales. Registered no. 3134634. VAT no.
> > > > GB927523612
> > > >
> > >
> > >
> >
>
>
>
> --
> -- Guozhang
>
