I see the reasoning and might be inclined to agree a bit :
If we go to stage 2, the only difference is that we can theoretically
support a null value non-tombstone message in a log compacted topic, but I
am not sure if that has any use case.

But as an end goal I see that kafka should clearly specify what it means by
a tombstone : is it the attribute flag OR is it the null value. If we just
do stage 1, I don't think we are defining the end-goal completely.
Again this is more about semantics of correctness of end state.

Thanks,

Mayuresh

On Wed, Nov 9, 2016 at 10:49 AM, Becket Qin <becket....@gmail.com> wrote:

> I am not sure if we need the second stage. Wouldn't it be enough to say
> that a message is a tombstone if one of the following is true?
> 1. tombstone flag is set.
> 2. value is null.
>
> If we go to stage 2, the only difference is that we can theoretically
> support a null value non-tombstone message in a log compacted topic, but I
> am not sure if that has any use case.
>
> Thanks,
>
> Jiangjie (Becket) Qin
>
>
> On Wed, Nov 9, 2016 at 9:23 AM, Mayuresh Gharat <
> gharatmayures...@gmail.com>
> wrote:
>
> > I think it will be a good idea. +1
> >
> > Thanks,
> >
> > Mayuresh
> >
> > On Wed, Nov 9, 2016 at 9:13 AM, Michael Pearce <michael.pea...@ig.com>
> > wrote:
> >
> > > +1 Mayuresh, I think this is a good solution/strategy.
> > >
> > > Shall we update the KIP with this? Becket/Jun/Joel any comments to add
> > > before we do?
> > >
> > > On 08/11/2016, 17:29, "Mayuresh Gharat" <gharatmayures...@gmail.com>
> > > wrote:
> > >
> > >     I think the migration can be done in 2 stages :
> > >
> > >     1) In first stage the broker should understand the attribute flag
> as
> > > well
> > >     as Null for the value for log compaction.
> > >     2) In second stage we move on to supporting only the attribute flag
> > > for log
> > >     compaction.
> > >
> > >     I agree with Becket that for older clients (consumers) the broker
> > might
> > >     have to down convert a message that has the attribute flag set for
> > log
> > >     compacting but has a non null value. But this should be in first
> > stage.
> > >     Once all the clients have upgraded (clients start recognizing the
> > > attribute
> > >     flag), we can move the broker to stage 2.
> > >
> > >     Thanks,
> > >
> > >     Mayuresh
> > >
> > >     On Tue, Nov 8, 2016 at 12:06 AM, Michael Pearce <
> > michael.pea...@ig.com
> > > >
> > >     wrote:
> > >
> > >     > Also we can add further guidance:
> > >     >
> > >     > To  avoid the below caveat to organisations by promoting of
> > > upgrading all
> > >     > consumers first before relying on producing tombstone messages
> with
> > > data
> > >     >
> > >     > Sent using OWA for iPhone
> > >     > ________________________________________
> > >     > From: Michael Pearce
> > >     > Sent: Tuesday, November 8, 2016 8:03:32 AM
> > >     > To: dev@kafka.apache.org
> > >     > Subject: Re: [DISCUSS] KIP-87 - Add Compaction Tombstone Flag
> > >     >
> > >     > Thanks Jun on the feedback, I think I understand the issue/point
> > now.
> > >     >
> > >     > We def can add that on older client version if tombstone marker
> > make
> > > the
> > >     > value null to preserve behaviour.
> > >     >
> > >     > There is one caveats to this:
> > >     >
> > >     > * we have to be clear that data is lost if reading via old
> > > client/message
> > >     > format - I don't think this is a big issue as mostly the idea/use
> > > case is
> > >     > around meta data transport as such would only be as bad as
> current
> > > situation
> > >     >
> > >     > Re having configurable broker this was to handle cases like you
> > > described
> > >     > but in another way by allowing organisation choose the behaviour
> of
> > > the
> > >     > compaction per broker or per topic so they could manage their
> > > transition to
> > >     > using tombstone markers.
> > >     >
> > >     > On hind sight it maybe easier to just upgrade and downgrade the
> > > messages
> > >     > on version as you propose.
> > >     >
> > >     >
> > >     >
> > >     >
> > >     >
> > >     >
> > >     > Sent using OWA for iPhone
> > >     > ________________________________________
> > >     > From: Jun Rao <j...@confluent.io>
> > >     > Sent: Tuesday, November 8, 2016 12:34:41 AM
> > >     > To: dev@kafka.apache.org
> > >     > Subject: Re: [DISCUSS] KIP-87 - Add Compaction Tombstone Flag
> > >     >
> > >     > For the use case, one potential use case is for schema
> > registration.
> > > For
> > >     > example, in Avro, a null value corresponds to a Null schema. So,
> if
> > > you
> > >     > want to be able to keep the schema id in a delete message, the
> > value
> > > can't
> > >     > be null. We could get around this issue by specializing null
> value
> > > during
> > >     > schema registration though.
> > >     >
> > >     > Now for the proposed changes. We probably should preserve client
> > >     > compatibility. If a client application is sending a null value
> to a
> > >     > compacted topic, ideally, it should work the same after the
> client
> > >     > upgrades.
> > >     >
> > >     > I am not sure about making the tombstone marker configurable,
> > > especially at
> > >     > the topic level. Should we allow users to change the config
> values
> > > back and
> > >     > forth, and what would be the implication?
> > >     >
> > >     > Thanks,
> > >     >
> > >     > Jun
> > >     >
> > >     > On Mon, Nov 7, 2016 at 10:48 AM, Becket Qin <
> becket....@gmail.com>
> > > wrote:
> > >     >
> > >     > > Hi Michael,
> > >     > >
> > >     > > Yes, changing the logic in the log cleaner makes sense. There
> > > could be
> > >     > some
> > >     > > other thing worth thinking (e.g. the message size change after
> > >     > conversion),
> > >     > > though.
> > >     > >
> > >     > > The scenario I was thinking is the following:
> > >     > > Imagine a distributed caching system built on top of Kafka. A
> > user
> > > is
> > >     > > consuming from a topic and it is guaranteed that if the user
> > > consume to
> > >     > the
> > >     > > log end it will get the latest value for all the keys.
> Currently
> > > if the
> > >     > > consumer sees a null value it knows the key has been removed.
> Now
> > > let's
> > >     > say
> > >     > > we rolled out this change. And the producer applies a message
> > with
> > > the
> > >     > > tombstone flag set, but the value was not null. When we append
> > that
> > >     > message
> > >     > > to the log I suppose we will not do the down conversion if the
> > > broker has
> > >     > > set the message.format.version to the latest. Because the log
> > > cleaner
> > >     > won't
> > >     > > touch the active log segment, so that message will be sitting
> in
> > > the
> > >     > active
> > >     > > segment as is. Now when a consumer that hasn't upgraded yet
> > > consumes that
> > >     > > tombstone message in the active segment, it seems that the
> broker
> > > will
> > >     > need
> > >     > > to down convert that message to remove the value, right? In
> this
> > > case, we
> > >     > > cannot wait for the log cleaner to do the down conversion
> because
> > > that
> > >     > > message may have already been consumed before the log
> compaction
> > > happens.
> > >     > >
> > >     > > Thanks,
> > >     > >
> > >     > > Jiangjie (Becket) Qin
> > >     > >
> > >     > >
> > >     > >
> > >     > > On Mon, Nov 7, 2016 at 9:59 AM, Michael Pearce <
> > > michael.pea...@ig.com>
> > >     > > wrote:
> > >     > >
> > >     > > > Hi Becket,
> > >     > > >
> > >     > > > We were thinking more about having the logic that’s in the
> > method
> > >     > > > shouldRetainMessage configurable via
> http://kafka.apache.org/
> > >     > > > documentation.html#brokerconfigs  at a broker/topic level.
> And
> > > then
> > >     > > scrap
> > >     > > > auto converting the message, and allow organisations to
> manage
> > > the
> > >     > > rollout
> > >     > > > of enabling of the feature.
> > >     > > > (this isn’t in documentation but in response to the
> discussion
> > > thread
> > >     > as
> > >     > > > an alternative approach to roll out the feature)
> > >     > > >
> > >     > > > Does this make any more sense?
> > >     > > >
> > >     > > > Thanks
> > >     > > > Mike
> > >     > > >
> > >     > > > On 11/3/16, 2:27 PM, "Becket Qin" <becket....@gmail.com>
> > wrote:
> > >     > > >
> > >     > > >     Hi Michael,
> > >     > > >
> > >     > > >     Do you mean using a new configuration it is just the
> > exiting
> > >     > > >     message.format.version config? It seems the
> > > message.format.version
> > >     > > > config
> > >     > > >     is enough in this case. And the default value would
> always
> > > be the
> > >     > > > latest
> > >     > > >     version.
> > >     > > >
> > >     > > >     > Message version migration would be handled as like in
> > > KIP-32
> > >     > > >
> > >     > > >     Also just want to confirm on this. Today if an old
> consumer
> > >     > consumes
> > >     > > a
> > >     > > > log
> > >     > > >     compacted topic and sees an empty value, it knows that
> is a
> > >     > > tombstone.
> > >     > > >     After we start to use the attribute bit, a tombstone
> > message
> > > can
> > >     > > have a
> > >     > > >     non-empty value. So by "like in KIP-32" you mean we will
> > > remove the
> > >     > > > value
> > >     > > >     to down convert the message if the consumer version is
> old,
> > > right?
> > >     > > >
> > >     > > >     Thanks.
> > >     > > >
> > >     > > >     Jiangjie (Becket) Qin
> > >     > > >
> > >     > > >     On Wed, Nov 2, 2016 at 1:37 AM, Michael Pearce <
> > >     > > michael.pea...@ig.com>
> > >     > > >     wrote:
> > >     > > >
> > >     > > >     > Hi Joel , et al.
> > >     > > >     >
> > >     > > >     > Any comments on the below idea to handle roll out /
> > > compatibility
> > >     > > of
> > >     > > > this
> > >     > > >     > feature, using a configuration?
> > >     > > >     >
> > >     > > >     > Does it make sense/clear?
> > >     > > >     > Does it add value?
> > >     > > >     > Do we want to enforce flag by default, or value by
> > > default, or
> > >     > > both?
> > >     > > >     >
> > >     > > >     > Cheers
> > >     > > >     > Mike
> > >     > > >     >
> > >     > > >     >
> > >     > > >     > On 10/27/16, 4:47 PM, "Michael Pearce" <
> > > michael.pea...@ig.com>
> > >     > > > wrote:
> > >     > > >     >
> > >     > > >     >     Thanks, James, I think this is a really good
> addition
> > > to the
> > >     > > KIP
> > >     > > >     > details, please feel free to amend the wiki/add the use
> > > cases,
> > >     > also
> > >     > > > if any
> > >     > > >     > others you think of. I definitely think its worthwhile
> > >     > documenting.
> > >     > > > If you
> > >     > > >     > can’t let me know ill add them next week (just leaving
> > for
> > > a long
> > >     > > > weekend
> > >     > > >     > off)
> > >     > > >     >
> > >     > > >     >     Re Joel and others comments about upgrade and
> > > compatibility.
> > >     > > >     >
> > >     > > >     >     Rather than trying to auto manage this.
> > >     > > >     >
> > >     > > >     >     Actually maybe we make a configuration option, both
> > at
> > > server
> > >     > > > and per
> > >     > > >     > topic level to control the behavior of how the server
> > logic
> > >     > should
> > >     > > > work out
> > >     > > >     > if the record, is a tombstone record .
> > >     > > >     >
> > >     > > >     >     e.g.
> > >     > > >     >
> > >     > > >     >     key = compation.tombstone.marker
> > >     > > >     >
> > >     > > >     >     value options:
> > >     > > >     >
> > >     > > >     >     value   (continues to use null value as tombstone
> > > marker)
> > >     > > >     >     flag (expects to use the tombstone flag)
> > >     > > >     >     value_or_flag (if either is true it treats the
> record
> > > as a
> > >     > > > tombstone)
> > >     > > >     >
> > >     > > >     >     This way on upgrade users can keep current
> behavior,
> > > and
> > >     > slowly
> > >     > > >     > migrate to the new. Having a transition period of using
> > >     > > > value_or_flag,
> > >     > > >     > finally having flag only if an organization wishes to
> use
> > > null
> > >     > > values
> > >     > > >     > without it being treated as a tombstone marker (use
> case
> > > noted
> > >     > > below)
> > >     > > >     >
> > >     > > >     >     Having it both global broker level and topic
> override
> > > also
> > >     > > > allows some
> > >     > > >     > flexibility here.
> > >     > > >     >
> > >     > > >     >     Cheers
> > >     > > >     >     Mike
> > >     > > >     >
> > >     > > >     >
> > >     > > >     >
> > >     > > >     >
> > >     > > >     >
> > >     > > >     >
> > >     > > >     >     On 10/27/16, 8:03 AM, "James Cheng" <
> > > wushuja...@gmail.com>
> > >     > > > wrote:
> > >     > > >     >
> > >     > > >     >         This KIP would definitely address a gap in the
> > > current
> > >     > > >     > functionality, where you currently can't have a
> tombstone
> > > with
> > >     > any
> > >     > > >     > associated content.
> > >     > > >     >
> > >     > > >     >         That said, I'd like to talk about use cases, to
> > > make sure
> > >     > > > that
> > >     > > >     > this is in fact useful. The KIP should be updated with
> > > whatever
> > >     > use
> > >     > > > cases
> > >     > > >     > we come up with.
> > >     > > >     >
> > >     > > >     >         First of all, an observation: When we speak
> about
> > > log
> > >     > > > compaction,
> > >     > > >     > we typically think of "the latest message for a key is
> > > retained".
> > >     > > In
> > >     > > > that
> > >     > > >     > respect, a delete tombstone (i.e. a message with a null
> > > payload)
> > >     > is
> > >     > > > treated
> > >     > > >     > the same as any other Kafka message: the latest message
> > is
> > >     > > retained.
> > >     > > > It
> > >     > > >     > doesn't matter whether the latest message is null, or
> if
> > > the
> > >     > latest
> > >     > > > message
> > >     > > >     > has actual content. In all cases, the last message is
> > > retained.
> > >     > > >     >
> > >     > > >     >         The only way a delete tombstone is treated
> > > differently
> > >     > from
> > >     > > > other
> > >     > > >     > Kafka messages is that it automatically disappears
> after
> > a
> > > while.
> > >     > > > The time
> > >     > > >     > of deletion is specified using delete.retention.ms.
> > >     > > >     >
> > >     > > >     >         So what we're really talking about is, do we
> want
> > > to
> > >     > > support
> > >     > > >     > messages in a log-compacted topic that auto-delete
> > > themselves
> > >     > after
> > >     > > > a while?
> > >     > > >     >
> > >     > > >     >         In a thread from 2015, there was a discussion
> on
> > >     > > first-class
> > >     > > >     > support of headers between Roger Hoover, Felix GV, Jun
> > > Rao, and
> > >     > I.
> > >     > > > See
> > >     > > >     > thread at https://groups.google.com/d/
> > > msg/confluent-platform/
> > >     > > >     > 8xPbjyUE_7E/yQ1AeCufL_gJ <https://groups.google.com/d/
> > >     > > >     > msg/confluent-platform/8xPbjyUE_7E/yQ1AeCufL_gJ> . In
> > that
> > >     > thread,
> > >     > > > Jun
> > >     > > >     > raised a good question that I didn't have a good answer
> > > for at
> > >     > the
> > >     > > > time: If
> > >     > > >     > a message is going to auto-delete itself after a while,
> > how
> > >     > > > important was
> > >     > > >     > the message? That is, what information did the message
> > > contain
> > >     > that
> > >     > > > was
> > >     > > >     > important *for a while* but not so important that it
> > > needed to be
> > >     > > > kept
> > >     > > >     > around forever?
> > >     > > >     >
> > >     > > >     >         Some use cases that I can think of:
> > >     > > >     >
> > >     > > >     >         1) Tracability. I would like to know who issued
> > > this
> > >     > delete
> > >     > > >     > tombstone. It might include the hostname, IP of the
> > > producer of
> > >     > the
> > >     > > > delete.
> > >     > > >     >         2) Timestamps. I would like to know when this
> > > delete was
> > >     > > > issued.
> > >     > > >     > This use case is already addressed by the availability
> of
> > >     > > per-message
> > >     > > >     > timestamps that came in 0.10.0
> > >     > > >     >         3) Data provenance. I hope I'm using this
> phrase
> > >     > correctly,
> > >     > > > but
> > >     > > >     > what I mean is, where did this delete come from? What
> > > processing
> > >     > > job
> > >     > > >     > emitted it? What input to the processing job caused
> this
> > > delete
> > >     > to
> > >     > > be
> > >     > > >     > produced? For example, if a record in topic A was
> > > processed and
> > >     > > > caused a
> > >     > > >     > delete tombstone to be emitted to topic B, I might like
> > the
> > >     > offset
> > >     > > > of the
> > >     > > >     > topic A message to be attached to the topic B message.
> > >     > > >     >         4) Distributed tracing for stream topologies.
> > This
> > > might
> > >     > > be a
> > >     > > >     > slight repeat of the above use cases. In the
> > microservices
> > > world,
> > >     > > we
> > >     > > > can
> > >     > > >     > generate call-graphs of webservices using tools like
> > > Zipkin/
> > >     > > > opentracing.io
> > >     > > >     > <http://opentracing.io/>, or something homegrown like
> > >     > > >     > https://engineering.linkedin.
> > com/distributed-service-call-
> > >     > > >     > graph/real-time-distributed-
> tracing-website-performance-
> > >     > > and-efficiency
> > >     > > > <
> > >     > > >     > https://engineering.linkedin.
> > com/distributed-service-call-
> > >     > > >     > graph/real-time-distributed-
> tracing-website-performance-
> > >     > > > and-efficiency>.
> > >     > > >     > I can imagine that you might want to do something
> similar
> > > for
> > >     > > stream
> > >     > > >     > processing topologies, where stream processing jobs
> carry
> > > along
> > >     > and
> > >     > > > forward
> > >     > > >     > along a globally unique identifier, and a distributed
> > > topology
> > >     > > graph
> > >     > > > is
> > >     > > >     > generated.
> > >     > > >     >         5) Cases where processing a delete requires
> data
> > > that is
> > >     > > not
> > >     > > >     > available in the message key. I'm not sure I have a
> good
> > > example
> > >     > of
> > >     > > > this,
> > >     > > >     > though. One hand-wavy example might be where I am
> > > publishing
> > >     > > > documents into
> > >     > > >     > Kafka where the documentId is the message key, and the
> > text
> > >     > > contents
> > >     > > > of the
> > >     > > >     > document are in the message body. And I have a
> consuming
> > > job that
> > >     > > > does some
> > >     > > >     > analytics on the message body. If that document gets
> > > deleted,
> > >     > then
> > >     > > > the
> > >     > > >     > consuming job might need the original message body in
> > > order to
> > >     > > > "delete"
> > >     > > >     > that message's impact from the analytics. But I'm not
> > sure
> > > that
> > >     > is
> > >     > > a
> > >     > > > great
> > >     > > >     > example. If the consumer was worried about that, the
> > > consumer
> > >     > would
> > >     > > >     > probably keep the original message around, stored by
> > > primary key.
> > >     > > > And then
> > >     > > >     > all it would need from a delete message would be the
> > > primary key
> > >     > of
> > >     > > > the
> > >     > > >     > message.
> > >     > > >     >
> > >     > > >     >         Do people think these are valid use cases?
> > >     > > >     >
> > >     > > >     >         What are other use cases that people can think
> > of?
> > >     > > >     >
> > >     > > >     >         -James
> > >     > > >     >
> > >     > > >     >         > On Oct 26, 2016, at 3:46 PM, Mayuresh Gharat
> <
> > >     > > >     > gharatmayures...@gmail.com> wrote:
> > >     > > >     >         >
> > >     > > >     >         > +1 @Joel.
> > >     > > >     >         > I think a clear migration plan of upgrading
> and
> > >     > > > downgrading of
> > >     > > >     > server and
> > >     > > >     >         > clients along with handling of issues that
> Joel
> > >     > > mentioned,
> > >     > > > on
> > >     > > >     > the KIP would
> > >     > > >     >         > be really great.
> > >     > > >     >         >
> > >     > > >     >         > Thanks,
> > >     > > >     >         >
> > >     > > >     >         > Mayuresh
> > >     > > >     >         >
> > >     > > >     >         > On Wed, Oct 26, 2016 at 3:31 PM, Joel Koshy <
> > >     > > > jjkosh...@gmail.com>
> > >     > > >     > wrote:
> > >     > > >     >         >
> > >     > > >     >         >> I'm not sure why it would be useful, but it
> > > should be
> > >     > > >     > theoretically
> > >     > > >     >         >> possible if the attribute bit alone is
> enough
> > > to mark
> > >     > a
> > >     > > >     > tombstone. OTOH, we
> > >     > > >     >         >> could consider that as invalid if we wish.
> > > These are
> > >     > > > relevant
> > >     > > >     > details that
> > >     > > >     >         >> I think should be added to the KIP.
> > >     > > >     >         >>
> > >     > > >     >         >> Also, in the few odd scenarios that I
> > mentioned
> > > we
> > >     > > should
> > >     > > > also
> > >     > > >     > consider
> > >     > > >     >         >> that fetches could be coming from other
> > >     > > yet-to-be-upgraded
> > >     > > >     > brokers in a
> > >     > > >     >         >> cluster that is being upgraded. So we would
> > > probably
> > >     > > want
> > >     > > > to
> > >     > > >     > continue to
> > >     > > >     >         >> support nulls as tombstones or down-convert
> in
> > > a way
> > >     > > that
> > >     > > > we
> > >     > > >     > are sure works
> > >     > > >     >         >> with least surprise to fetchers.
> > >     > > >     >         >>
> > >     > > >     >         >> There is a slightly vague statement under
> > >     > > "Compatibility,
> > >     > > >     > Deprecation, and
> > >     > > >     >         >> Migration Plan" that could benefit more
> > details:
> > >     > *Logic
> > >     > > > would
> > >     > > >     > base on
> > >     > > >     >         >> current behavior of null value or if
> tombstone
> > > flag
> > >     > set
> > >     > > to
> > >     > > >     > true, as such
> > >     > > >     >         >> wouldn't impact any existing flows simply
> > allow
> > > new
> > >     > > > producers
> > >     > > >     > to make use
> > >     > > >     >         >> of the feature*. It is unclear to me based
> on
> > > that
> > >     > > > whether you
> > >     > > >     > would
> > >     > > >     >         >> interpret null as a tombstone if the
> tombstone
> > >     > attribute
> > >     > > > bit is
> > >     > > >     > off.
> > >     > > >     >         >>
> > >     > > >     >         >> On Wed, Oct 26, 2016 at 3:10 PM, Xavier
> > Léauté <
> > >     > > >     > xav...@confluent.io>
> > >     > > >     >         >> wrote:
> > >     > > >     >         >>
> > >     > > >     >         >>> Does this mean that starting with V4
> requests
> > > we
> > >     > would
> > >     > > > allow
> > >     > > >     > storing null
> > >     > > >     >         >>> messages in compacted topics? The KIP
> should
> > > probably
> > >     > > > clarify
> > >     > > >     > the
> > >     > > >     >         >> behavior
> > >     > > >     >         >>> for null messages where the tombstone flag
> is
> > > not
> > >     > net.
> > >     > > >     >         >>>
> > >     > > >     >         >>> On Wed, Oct 26, 2016 at 1:32 AM Magnus
> > > Edenhill <
> > >     > > >     > mag...@edenhill.se>
> > >     > > >     >         >>> wrote:
> > >     > > >     >         >>>
> > >     > > >     >         >>>> 2016-10-25 21:36 GMT+02:00 Nacho Solis
> > >     > > >     > <nso...@linkedin.com.invalid>:
> > >     > > >     >         >>>>
> > >     > > >     >         >>>>> I think you probably require a MagicByte
> > > bump if
> > >     > you
> > >     > > > expect
> > >     > > >     > correct
> > >     > > >     >         >>>>> behavior of the system as a whole.
> > >     > > >     >         >>>>>
> > >     > > >     >         >>>>> From a client perspective you want to
> make
> > > sure
> > >     > that
> > >     > > > when you
> > >     > > >     >         >> deliver a
> > >     > > >     >         >>>>> message that the broker supports the
> > feature
> > > you're
> > >     > > > expecting
> > >     > > >     >         >>>>> (compaction).  So, depending on the
> > behavior
> > > of the
> > >     > > > broker on
> > >     > > >     >         >>>> encountering
> > >     > > >     >         >>>>> a previously undefined bit flag I would
> > > suggest
> > >     > > making
> > >     > > > some
> > >     > > >     > change to
> > >     > > >     >         >>>> make
> > >     > > >     >         >>>>> certain that flag-based compaction is
> > > supported.
> > >     > I'm
> > >     > > > going
> > >     > > >     > to guess
> > >     > > >     >         >>> that
> > >     > > >     >         >>>>> the MagicByte would do this.
> > >     > > >     >         >>>>>
> > >     > > >     >         >>>>
> > >     > > >     >         >>>> I dont believe this is needed since it is
> > > already
> > >     > > > attributed
> > >     > > >     > through
> > >     > > >     >         >> the
> > >     > > >     >         >>>> request's API version.
> > >     > > >     >         >>>>
> > >     > > >     >         >>>> Producer:
> > >     > > >     >         >>>> * if a client sends ProduceRequest V4 then
> > >     > > > attributes.bit5
> > >     > > >     > indicates a
> > >     > > >     >         >>>> tombstone
> > >     > > >     >         >>>> * if a clients sends ProduceRequest <V4
> then
> > >     > > > attributes.bit5
> > >     > > >     > is
> > >     > > >     >         >> ignored
> > >     > > >     >         >>>> and value==null indicates a tombstone
> > >     > > >     >         >>>> * in both cases the on-disk messages are
> > > stored with
> > >     > > >     > attributes.bit5
> > >     > > >     >         >> (I
> > >     > > >     >         >>>> assume?)
> > >     > > >     >         >>>>
> > >     > > >     >         >>>> Consumer:
> > >     > > >     >         >>>> * if a clients sends FetchRequest V4
> > messages
> > > are
> > >     > > >     > sendfile():ed
> > >     > > >     >         >> directly
> > >     > > >     >         >>>> from disk (with attributes.bit5)
> > >     > > >     >         >>>> * if a client sends FetchRequest <V4
> > messages
> > > are
> > >     > > > slowpathed
> > >     > > >     > and
> > >     > > >     >         >>>> translated from attributes.bit5 to
> > value=null
> > > as
> > >     > > > required.
> > >     > > >     >         >>>>
> > >     > > >     >         >>>>
> > >     > > >     >         >>>> That's my understanding anyway, please
> > > correct me if
> > >     > > I'm
> > >     > > >     > wrong.
> > >     > > >     >         >>>>
> > >     > > >     >         >>>> /Magnus
> > >     > > >     >         >>>>
> > >     > > >     >         >>>>
> > >     > > >     >         >>>>
> > >     > > >     >         >>>>> On Tue, Oct 25, 2016 at 10:17 AM, Magnus
> > > Edenhill <
> > >     > > >     >         >> mag...@edenhill.se>
> > >     > > >     >         >>>>> wrote:
> > >     > > >     >         >>>>>
> > >     > > >     >         >>>>>> It is safe to assume that a previously
> > > undefined
> > >     > > > attributes
> > >     > > >     > bit
> > >     > > >     >         >> will
> > >     > > >     >         >>> be
> > >     > > >     >         >>>>>> unset in protocol requests from existing
> > > clients,
> > >     > if
> > >     > > > not,
> > >     > > >     > such a
> > >     > > >     >         >>> client
> > >     > > >     >         >>>>> is
> > >     > > >     >         >>>>>> already violating the protocol and needs
> > to
> > > be
> > >     > > fixed.
> > >     > > >     >         >>>>>>
> > >     > > >     >         >>>>>> So I dont see a need for a MagicByte
> bump,
> > > both
> > >     > > > broker and
> > >     > > >     > client
> > >     > > >     >         >> has
> > >     > > >     >         >>>> the
> > >     > > >     >         >>>>>> information it needs to construct or
> parse
> > > the
> > >     > > message
> > >     > > >     > according to
> > >     > > >     >         >>>>> request
> > >     > > >     >         >>>>>> version.
> > >     > > >     >         >>>>>>
> > >     > > >     >         >>>>>>
> > >     > > >     >         >>>>>> 2016-10-25 18:48 GMT+02:00 Michael
> Pearce
> > <
> > >     > > >     > michael.pea...@ig.com>:
> > >     > > >     >         >>>>>>
> > >     > > >     >         >>>>>>> Hi Magnus,
> > >     > > >     >         >>>>>>>
> > >     > > >     >         >>>>>>> I was wondering if I even needed to
> > change
> > > those
> > >     > > > also, as
> > >     > > >     >         >>> technically
> > >     > > >     >         >>>>>>> we’re just making use of a non used
> > > attribute
> > >     > bit,
> > >     > > > but im
> > >     > > >     > not
> > >     > > >     >         >> 100%
> > >     > > >     >         >>>> that
> > >     > > >     >         >>>>>> it
> > >     > > >     >         >>>>>>> be always false currently.
> > >     > > >     >         >>>>>>>
> > >     > > >     >         >>>>>>> If someone can say 100% it will already
> > be
> > > set
> > >     > > false
> > >     > > > with
> > >     > > >     > current
> > >     > > >     >         >>> and
> > >     > > >     >         >>>>>>> historic bit wise masking techniques
> used
> > > over
> > >     > the
> > >     > > > time,
> > >     > > >     > we could
> > >     > > >     >         >>> do
> > >     > > >     >         >>>>> away
> > >     > > >     >         >>>>>>> with both, and simply just start to use
> > it.
> > >     > > > Unfortunately
> > >     > > >     > I don’t
> > >     > > >     >         >>>> have
> > >     > > >     >         >>>>>> that
> > >     > > >     >         >>>>>>> historic knowledge so was hoping it
> would
> > > be
> > >     > > flagged
> > >     > > > up in
> > >     > > >     > this
> > >     > > >     >         >>>>>> discussion
> > >     > > >     >         >>>>>>> thread ?
> > >     > > >     >         >>>>>>>
> > >     > > >     >         >>>>>>> Cheers
> > >     > > >     >         >>>>>>> Mike
> > >     > > >     >         >>>>>>>
> > >     > > >     >         >>>>>>> On 10/25/16, 5:36 PM, "Magnus
> Edenhill" <
> > >     > > >     > mag...@edenhill.se>
> > >     > > >     >         >>> wrote:
> > >     > > >     >         >>>>>>>
> > >     > > >     >         >>>>>>>    Hi Michael,
> > >     > > >     >         >>>>>>>
> > >     > > >     >         >>>>>>>    With the version bumps for Produce
> and
> > > Fetch
> > >     > > > requests,
> > >     > > >     > do you
> > >     > > >     >         >>>>> really
> > >     > > >     >         >>>>>>> need
> > >     > > >     >         >>>>>>>    to bump MagicByte too?
> > >     > > >     >         >>>>>>>
> > >     > > >     >         >>>>>>>    Regards,
> > >     > > >     >         >>>>>>>    Magnus
> > >     > > >     >         >>>>>>>
> > >     > > >     >         >>>>>>>
> > >     > > >     >         >>>>>>>    2016-10-25 18:09 GMT+02:00 Michael
> > > Pearce <
> > >     > > >     >         >>> michael.pea...@ig.com
> > >     > > >     >         >>>>> :
> > >     > > >     >         >>>>>>>
> > >     > > >     >         >>>>>>>> Hi All,
> > >     > > >     >         >>>>>>>>
> > >     > > >     >         >>>>>>>> I would like to discuss the following
> > KIP
> > >     > > proposal:
> > >     > > >     >         >>>>>>>> https://cwiki.apache.org/
> > >     > > > confluence/display/KAFKA/KIP-
> > >     > > >     >         >>>>>>>> 87+-+Add+Compaction+Tombstone+Flag
> > >     > > >     >         >>>>>>>>
> > >     > > >     >         >>>>>>>> This is off the back of the discussion
> > on
> > > KIP-82
> > >     > > /
> > >     > > > KIP
> > >     > > >     >         >>> meeting
> > >     > > >     >         >>>>>>> where it
> > >     > > >     >         >>>>>>>> was agreed to separate this issue and
> > > feature.
> > >     > > See:
> > >     > > >     >         >>>>>>>> http://mail-archives.apache.
> > >     > > > org/mod_mbox/kafka-dev/201610
> > >     > > >     > .
> > >     > > >     >         >>>>>>>> mbox/%3cCAJS3ho8OcR==
> > > EcxsJ8OP99pD2hz=iiGecWsv-
> > >     > > >     >         >>>>>>>> EZsBsNyDcKr=g...@mail.gmail.com%3e
> > >     > > >     >         >>>>>>>>
> > >     > > >     >         >>>>>>>> Thanks
> > >     > > >     >         >>>>>>>> Mike
> > >     > > >     >         >>>>>>>>
> > >     > > >     >         >>>>>>>> The information contained in this
> email
> > is
> > >     > > strictly
> > >     > > >     >         >>>> confidential
> > >     > > >     >         >>>>>> and
> > >     > > >     >         >>>>>>> for
> > >     > > >     >         >>>>>>>> the use of the addressee only, unless
> > > otherwise
> > >     > > > indicated.
> > >     > > >     >         >> If
> > >     > > >     >         >>>> you
> > >     > > >     >         >>>>>>> are not
> > >     > > >     >         >>>>>>>> the intended recipient, please do not
> > > read,
> > >     > copy,
> > >     > > > use or
> > >     > > >     >         >>>> disclose
> > >     > > >     >         >>>>>> to
> > >     > > >     >         >>>>>>> others
> > >     > > >     >         >>>>>>>> this message or any attachment. Please
> > > also
> > >     > notify
> > >     > > > the
> > >     > > >     >         >> sender
> > >     > > >     >         >>>> by
> > >     > > >     >         >>>>>>> replying
> > >     > > >     >         >>>>>>>> to this email or by telephone (+44(020
> > > 7896
> > >     > 0011)
> > >     > > > and then
> > >     > > >     >         >>>> delete
> > >     > > >     >         >>>>>>> the email
> > >     > > >     >         >>>>>>>> and any copies of it. Opinions,
> > > conclusion (etc)
> > >     > > > that do
> > >     > > >     >         >> not
> > >     > > >     >         >>>>> relate
> > >     > > >     >         >>>>>>> to the
> > >     > > >     >         >>>>>>>> official business of this company
> shall
> > be
> > >     > > > understood as
> > >     > > >     >         >>>> neither
> > >     > > >     >         >>>>>>> given nor
> > >     > > >     >         >>>>>>>> endorsed by it. IG is a trading name
> of
> > IG
> > >     > Markets
> > >     > > > Limited
> > >     > > >     >         >> (a
> > >     > > >     >         >>>>>> company
> > >     > > >     >         >>>>>>>> registered in England and Wales,
> company
> > > number
> > >     > > > 04008957)
> > >     > > >     >         >> and
> > >     > > >     >         >>>> IG
> > >     > > >     >         >>>>>>> Index
> > >     > > >     >         >>>>>>>> Limited (a company registered in
> England
> > > and
> > >     > > Wales,
> > >     > > >     > company
> > >     > > >     >         >>>>> number
> > >     > > >     >         >>>>>>>> 01190902). Registered address at
> Cannon
> > > Bridge
> > >     > > > House, 25
> > >     > > >     >         >>>> Dowgate
> > >     > > >     >         >>>>>>> Hill,
> > >     > > >     >         >>>>>>>> London EC4R 2YA. Both IG Markets
> Limited
> > >     > (register
> > >     > > > number
> > >     > > >     >         >>>> 195355)
> > >     > > >     >         >>>>>>> and IG
> > >     > > >     >         >>>>>>>> Index Limited (register number 114059)
> > are
> > >     > > > authorised and
> > >     > > >     >         >>>>> regulated
> > >     > > >     >         >>>>>>> by the
> > >     > > >     >         >>>>>>>> Financial Conduct Authority.
> > >     > > >     >         >>>>>>>>
> > >     > > >     >         >>>>>>>
> > >     > > >     >         >>>>>>>
> > >     > > >     >         >>>>>>> The information contained in this email
> > is
> > >     > strictly
> > >     > > >     > confidential
> > >     > > >     >         >>> and
> > >     > > >     >         >>>>> for
> > >     > > >     >         >>>>>>> the use of the addressee only, unless
> > > otherwise
> > >     > > > indicated.
> > >     > > >     > If you
> > >     > > >     >         >>> are
> > >     > > >     >         >>>>> not
> > >     > > >     >         >>>>>>> the intended recipient, please do not
> > > read, copy,
> > >     > > > use or
> > >     > > >     > disclose
> > >     > > >     >         >>> to
> > >     > > >     >         >>>>>> others
> > >     > > >     >         >>>>>>> this message or any attachment. Please
> > also
> > >     > notify
> > >     > > > the
> > >     > > >     > sender by
> > >     > > >     >         >>>>> replying
> > >     > > >     >         >>>>>>> to this email or by telephone (+44(020
> > > 7896 0011)
> > >     > > > and then
> > >     > > >     > delete
> > >     > > >     >         >>> the
> > >     > > >     >         >>>>>> email
> > >     > > >     >         >>>>>>> and any copies of it. Opinions,
> > conclusion
> > > (etc)
> > >     > > > that do
> > >     > > >     > not
> > >     > > >     >         >> relate
> > >     > > >     >         >>>> to
> > >     > > >     >         >>>>>> the
> > >     > > >     >         >>>>>>> official business of this company shall
> > be
> > >     > > > understood as
> > >     > > >     > neither
> > >     > > >     >         >>>> given
> > >     > > >     >         >>>>>> nor
> > >     > > >     >         >>>>>>> endorsed by it. IG is a trading name of
> > IG
> > >     > Markets
> > >     > > > Limited
> > >     > > >     > (a
> > >     > > >     >         >>> company
> > >     > > >     >         >>>>>>> registered in England and Wales,
> company
> > > number
> > >     > > > 04008957)
> > >     > > >     > and IG
> > >     > > >     >         >>>> Index
> > >     > > >     >         >>>>>>> Limited (a company registered in
> England
> > > and
> > >     > Wales,
> > >     > > > company
> > >     > > >     >         >> number
> > >     > > >     >         >>>>>>> 01190902). Registered address at Cannon
> > > Bridge
> > >     > > > House, 25
> > >     > > >     > Dowgate
> > >     > > >     >         >>>> Hill,
> > >     > > >     >         >>>>>>> London EC4R 2YA. Both IG Markets
> Limited
> > >     > (register
> > >     > > > number
> > >     > > >     > 195355)
> > >     > > >     >         >>> and
> > >     > > >     >         >>>>> IG
> > >     > > >     >         >>>>>>> Index Limited (register number 114059)
> > are
> > >     > > > authorised and
> > >     > > >     >         >> regulated
> > >     > > >     >         >>>> by
> > >     > > >     >         >>>>>> the
> > >     > > >     >         >>>>>>> Financial Conduct Authority.
> > >     > > >     >         >>>>>>>
> > >     > > >     >         >>>>>>
> > >     > > >     >         >>>>>
> > >     > > >     >         >>>>>
> > >     > > >     >         >>>>>
> > >     > > >     >         >>>>> --
> > >     > > >     >         >>>>> Nacho (Ignacio) Solis
> > >     > > >     >         >>>>> Kafka
> > >     > > >     >         >>>>> nso...@linkedin.com
> > >     > > >     >         >>>>>
> > >     > > >     >         >>>>
> > >     > > >     >         >>>
> > >     > > >     >         >>
> > >     > > >     >         >
> > >     > > >     >         >
> > >     > > >     >         >
> > >     > > >     >         > --
> > >     > > >     >         > -Regards,
> > >     > > >     >         > Mayuresh R. Gharat
> > >     > > >     >         > (862) 250-7125
> > >     > > >     >
> > >     > > >     >
> > >     > > >     >
> > >     > > >     >     The information contained in this email is strictly
> > >     > > confidential
> > >     > > > and
> > >     > > >     > for the use of the addressee only, unless otherwise
> > > indicated. If
> > >     > > > you are
> > >     > > >     > not the intended recipient, please do not read, copy,
> use
> > > or
> > >     > > > disclose to
> > >     > > >     > others this message or any attachment. Please also
> notify
> > > the
> > >     > > sender
> > >     > > > by
> > >     > > >     > replying to this email or by telephone (+44(020 7896
> > 0011)
> > > and
> > >     > then
> > >     > > > delete
> > >     > > >     > the email and any copies of it. Opinions, conclusion
> > (etc)
> > > that
> > >     > do
> > >     > > > not
> > >     > > >     > relate to the official business of this company shall
> be
> > >     > understood
> > >     > > > as
> > >     > > >     > neither given nor endorsed by it. IG is a trading name
> of
> > > IG
> > >     > > Markets
> > >     > > >     > Limited (a company registered in England and Wales,
> > company
> > >     > number
> > >     > > >     > 04008957) and IG Index Limited (a company registered in
> > > England
> > >     > and
> > >     > > > Wales,
> > >     > > >     > company number 01190902). Registered address at Cannon
> > > Bridge
> > >     > > House,
> > >     > > > 25
> > >     > > >     > Dowgate Hill, London EC4R 2YA. Both IG Markets Limited
> > > (register
> > >     > > > number
> > >     > > >     > 195355) and IG Index Limited (register number 114059)
> are
> > >     > > authorised
> > >     > > > and
> > >     > > >     > regulated by the Financial Conduct Authority.
> > >     > > >     >
> > >     > > >     >
> > >     > > >     >
> > >     > > >
> > >     > > >
> > >     > > > The information contained in this email is strictly
> > confidential
> > > and
> > >     > for
> > >     > > > the use of the addressee only, unless otherwise indicated. If
> > > you are
> > >     > not
> > >     > > > the intended recipient, please do not read, copy, use or
> > > disclose to
> > >     > > others
> > >     > > > this message or any attachment. Please also notify the sender
> > by
> > >     > replying
> > >     > > > to this email or by telephone (+44(020 7896 0011) and then
> > > delete the
> > >     > > email
> > >     > > > and any copies of it. Opinions, conclusion (etc) that do not
> > > relate to
> > >     > > the
> > >     > > > official business of this company shall be understood as
> > neither
> > > given
> > >     > > nor
> > >     > > > endorsed by it. IG is a trading name of IG Markets Limited (a
> > > company
> > >     > > > registered in England and Wales, company number 04008957) and
> > IG
> > > Index
> > >     > > > Limited (a company registered in England and Wales, company
> > > number
> > >     > > > 01190902). Registered address at Cannon Bridge House, 25
> > Dowgate
> > > Hill,
> > >     > > > London EC4R 2YA. Both IG Markets Limited (register number
> > > 195355) and
> > >     > IG
> > >     > > > Index Limited (register number 114059) are authorised and
> > > regulated by
> > >     > > the
> > >     > > > Financial Conduct Authority.
> > >     > > >
> > >     > >
> > >     > The information contained in this email is strictly confidential
> > and
> > > for
> > >     > the use of the addressee only, unless otherwise indicated. If you
> > > are not
> > >     > the intended recipient, please do not read, copy, use or disclose
> > to
> > > others
> > >     > this message or any attachment. Please also notify the sender by
> > > replying
> > >     > to this email or by telephone (+44(020 7896 0011) and then delete
> > > the email
> > >     > and any copies of it. Opinions, conclusion (etc) that do not
> relate
> > > to the
> > >     > official business of this company shall be understood as neither
> > > given nor
> > >     > endorsed by it. IG is a trading name of IG Markets Limited (a
> > company
> > >     > registered in England and Wales, company number 04008957) and IG
> > > Index
> > >     > Limited (a company registered in England and Wales, company
> number
> > >     > 01190902). Registered address at Cannon Bridge House, 25 Dowgate
> > > Hill,
> > >     > London EC4R 2YA. Both IG Markets Limited (register number 195355)
> > > and IG
> > >     > Index Limited (register number 114059) are authorised and
> regulated
> > > by the
> > >     > Financial Conduct Authority.
> > >     >
> > >
> > >
> > >
> > >     --
> > >     -Regards,
> > >     Mayuresh R. Gharat
> > >     (862) 250-7125
> > >
> > >
> > > The information contained in this email is strictly confidential and
> for
> > > the use of the addressee only, unless otherwise indicated. If you are
> not
> > > the intended recipient, please do not read, copy, use or disclose to
> > others
> > > this message or any attachment. Please also notify the sender by
> replying
> > > to this email or by telephone (+44(020 7896 0011) and then delete the
> > email
> > > and any copies of it. Opinions, conclusion (etc) that do not relate to
> > the
> > > official business of this company shall be understood as neither given
> > nor
> > > endorsed by it. IG is a trading name of IG Markets Limited (a company
> > > registered in England and Wales, company number 04008957) and IG Index
> > > Limited (a company registered in England and Wales, company number
> > > 01190902). Registered address at Cannon Bridge House, 25 Dowgate Hill,
> > > London EC4R 2YA. Both IG Markets Limited (register number 195355) and
> IG
> > > Index Limited (register number 114059) are authorised and regulated by
> > the
> > > Financial Conduct Authority.
> > >
> >
> >
> >
> > --
> > -Regards,
> > Mayuresh R. Gharat
> > (862) 250-7125
> >
>



-- 
-Regards,
Mayuresh R. Gharat
(862) 250-7125

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