A quick differentiation I would like to make is null is not the same as size 0.
Many times these are made equal, but they're not. When serializing data, we have to make a choice in null values and many times these are translated to zero length blobs. This is not really the same thing. >From this perspective, what can Kafka represent and what is considered a valid value? If the user sends a byte array of length 0, or if the serializer sends something of length 0, this should be a valid value. It is not kafka's job to determine what the user is trying to send. For all we know, the user has a really good compression serializer that sends 0 bytes when nothing has changed. If the user is allowed to send null then some behavior should be defined. However, this should semantically be different than sending a command. It is possible for a null value could signify some form of delete, like "delete all messages with this key". However, if kafka has a goal to write good, readable code, then this should not be allowed. A delete or a purge is a call that can have certain side effects or encounter errors that are unrelated to a send call. A couple of bullets from the Kafka style guide ( http://kafka.apache.org/coding-guide.html ): - Clear code is preferable to comments. When possible make your naming so good you don't need comments. - Logging, configuration, and public APIs are our "UI". Make them pretty, consistent, and usable. If you want sendTombstone() functionality make the protocol reflect that. Right now we're struggling because we did not have a clear separation of concerns. I don't have a good solution for deployment. I'm in favor of a harsh road: - Add the flag/variable/header for tombstone - Add an API for tombstone behavior if needed - Error if somebody tries to API send null - Accept if somebody tries to API send byte[] length 0 - Rev broker version - broker accept flag/variable/header as tombstone - broker accept zero length values as normal messages The more gentle road would be: - Add the flag/variable/header for tombstone - Add an API for tombstone behavior if needed - warn/deprecate/etc if somebody sends null - broker accepts flags/variable/headers and zero length values as tombstones Conversion from one to the other may be possible but I would rather not have to do it. Nacho On Wed, Nov 9, 2016 at 9:03 PM, radai <radai.rosenbl...@gmail.com> wrote: > my personal opinion - a log compacted topic is basically a kv-store, so a > map API. > map.put(key, null) is not the same as map.remove(key), which to me means a > null value should not represent a delete. a delete should be explicit > (meaning flag). > > > On Wed, Nov 9, 2016 at 11:01 AM, Mayuresh Gharat < > gharatmayures...@gmail.com > > wrote: > > > 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 > > > -- Nacho - Ignacio Solis - iso...@igso.net
