Hi all, I will start the vote thread shortly for this updated KIP. If there are any more thoughts I would love to hear them.
Thanks, Senthil -----Original Message----- From: Senthilnathan Muthusamy <senth...@microsoft.com.INVALID> Sent: Thursday, October 31, 2019 3:51 AM To: dev@kafka.apache.org Subject: RE: [DISCUSS] KIP-280: Enhanced log compaction Hi Matthias Thanks for the response. (1) Yes (2) Yes, and the config name will be the same (i.e. `log.cleaner.compaction.strategy` & `log.cleaner.compaction.strategy.header`) at broker level and topic level (to override broker level default compact strategy). Please let me know if we need to keep it in different naming convention. Note: Broker level (which will be in the server.properties) configuration is optional and default it to offset. Topic level configuration will be default to broker level config... (3) By this new way, it avoids another config parameter and also in feature if any new strategy like header need addition info, no additional config required. As this got discussed already and agreed to have separate config, I will revert it. KIP updated... (4) Done (5) Updated (6) Updated to pick the first header in the list Please let me know if you have any other questions. Thanks, Senthil -----Original Message----- From: Matthias J. Sax <matth...@confluent.io> Sent: Thursday, October 31, 2019 12:13 AM To: dev@kafka.apache.org Subject: Re: [DISCUSS] KIP-280: Enhanced log compaction Thanks for picking up this KIP, Senthil. (1) As far as I remember, the main issue of the original proposal was a missing topic level configuration for the compaction strategy. With this being addressed, I am in favor of this KIP. (2) With regard to (1), it seems we would need a new topic level config `compaction.strategy`, and `log.cleaner.compaction.strategy` would be the default strategy (ie, broker level config) if a topic does not overwrite it? (3) Why did you remove `log.cleaner.compaction.strategy.header` parameter and change the accepted values of `log.cleaner.compaction.strategy` to "header.<key>" instead of keeping "header"? The original approach seems to be cleaner, and I think this was discussed on the original discuss thread already. (4) Nit: For the "timestamp" compaction strategy you changed the KIP to -> `The record [create] timestamp` This is miss leading IMHO, because it depends on the broker/log configuration `(log.)message.timestamp.type` that can either be `CreateTime` or `LogAppendTime` what the actual record timestamp is. I would just remove "create" to keep it unspecified. (5) Nit: the section "Public Interfaces" should list the newly introduced configs -- configuration parameters are a public interface. (6) What do you mean by "first level header lookup"? The term "first level" indicates some hierarchy, but headers don't have any hierarchy -- it's just a list of key-value pairs? If you mean the _order_ of the headers, ie, pick the first header in the list that matches the key, please rephrase it to make it clearer. @Tom: I agree with all you are saying, however, I still think that this KIP will improve the overall situation, because everything you pointed out is actually true with offset based compaction, too. The KIP is not a silver bullet that solves all issue for interleaved writes, but I personally believe, it's a good improvement. -Matthias On 10/30/19 9:45 AM, Senthilnathan Muthusamy wrote: > Hi, > > Please let me know if anyone has any questions on this updated KIP-280... > > Thanks, > > Senthil > > -----Original Message----- > From: Senthilnathan Muthusamy <senth...@microsoft.com.INVALID> > Sent: Monday, October 28, 2019 11:36 PM > To: dev@kafka.apache.org > Subject: RE: [DISCUSS] KIP-280: Enhanced log compaction > > Hi Tom, > > Sorry for the delayed response. > > Regarding the fall back to offset decision for both timestamp & header value > is based on the previous author discuss > https://nam06.safelinks.protection.outlook.com/?url=https%3A%2F%2Flists.apache.org%2Fthread.html%2Ff44317eb6cd34f91966654c80509d4a457dbbccdd02b86645782be67%40%253Cdev.kafka.apache.org%253E&data=02%7C01%7Csenthilm%40microsoft.com%7Cb5c596140be1436e9fb708d75df04714%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C637081159484181661&sdata=%2Fap4F2CdPQe02wNDGkzjzIrxOQRTa2KraQE75dpjTzE%3D&reserved=0 > and as per the discussion, it is really required to avoid duplicates. > > And the timestamp strategy is from the original KIP author and we are keeping > it as is. > > Finally on the sequence order guarantee by the producer, it is not feasible > on waiting for ack in async / multi-threads/processes scenarios and hence the > header sequence based compact strategy with producer's responsibility to have > a unique sequence generation for the topic-partition-key level. > > Hoping this clarifies all your questions. Please let us know if you have any > further questions. > > @Guozhang Wang / @Matthias J. Sax, I see you both had a detail discussion on > the original KIP with previous author and it would great to hear your inputs > as well. > > Thanks, > Senthil > > -----Original Message----- > From: Tom Bentley <tbent...@redhat.com> > Sent: Tuesday, October 22, 2019 2:32 AM > To: dev@kafka.apache.org > Subject: Re: [DISCUSS] KIP-280: Enhanced log compaction > > Hi Senthilnathan, > > In the motivation isn't it a little misleading to say "On the producer > side, we clearly preserve an order for the two messages, <K1, V1> <K1, > V2>"? IMHO, the semantics of the producer are clear that having an > V2>observed > order of sending records from different producers is not sufficient to > guarantee ordering on the broker. You really need to send the 2nd record only > after the 1st record is acked. It's the difficultly of achieving that in > practice that's the true motivation for your KIP. > > I can see the attraction of using timestamps, but it would be helpful to > explain how that really solves the problem. When the producers are in > different processes on different machines you're relying on their clocks > being synchronized, which is a whole subject in itself. Even if they're > synchronized the resolution of System.currentTimeMillis() is typically many > milliseconds. If your producers are in different threads of the same process > that could be a real problem because it makes ties quite likely. > And you don't explain why it's OK to resolve ties using the offset. The basis > of your argument is that the offset is giving you the wrong answer. > So it seems to me that using it as a tiebreaker is just narrowing the chances > of getting the wrong answer. Maybe none of this matters for your use case, > but I think it should be spelled out in the KIP, because it surely would > matter for similar use cases. > > Using a sequence at least removes the problem of ties, but the interesting > bit is now in how you deal with races between threads/processes in getting a > sequence number allocated (which is out of scope of the KIP, I guess). > How is resolving that race any simpler that resolving the motivating race by > waiting for the ack of the first record sent? > > Kind regards, > > Tom > > On Mon, Oct 21, 2019 at 9:06 PM Senthilnathan Muthusamy > <senth...@microsoft.com.invalid> wrote: > >> Hi All, >> >> We are bring back the KIP-280 to live with small correct for the >> discussion & voting. Thanks to previous author Luis Cabral on the >> KIP-280 initiation and we are taking over to complete and get it into 2.4... >> >> Below is the correction that we made to the existing KIP-280: >> >> * Allowing the compact strategy configuration at the topic level as >> the log compaction is at the topic level and a broker can have >> multiple topics. This allows the flexibility to have the strategy at >> both broker level (i.e. for all topics within the broker) and topic >> level (i.e. for a subset of topics within a broker) as well... >> >> KIP-280: >> https://nam06.safelinks.protection.outlook.com/?url=https%3A%2F%2Fcwi >> k >> i.apache.org%2Fconfluence%2Fdisplay%2FKAFKA%2FKIP-280%253A%2BEnhanced >> % >> 2Blog%2Bcompaction&data=02%7C01%7Csenthilm%40microsoft.com%7C686c >> 3 >> 2fa4a554d61ae1408d756d409f6%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C >> 0 >> %7C637073341017520406&sdata=KrRem2KWCBscHX963Ah8wZ%2Fj9dkhCeAa7Gs >> 6 >> XqJ%2F5SQ%3D&reserved=0 PULL REQUEST: >> https://nam06.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgit >> h >> ub.com%2Fapache%2Fkafka%2Fpull%2F7528&data=02%7C01%7Csenthilm%40m >> i >> crosoft.com%7C686c32fa4a554d61ae1408d756d409f6%7C72f988bf86f141af91ab >> 2 >> d7cd011db47%7C1%7C0%7C637073341017520406&sdata=bt32PgDUjJjpXohEWp >> t >> Fxv6mPERCwcRFlVROzinBtnk%3D&reserved=0 (unit test coverage in >> progress) >> >> Previous Thread DISCUSS: >> https://nam06.safelinks.protection.outlook.com/?url=https%3A%2F%2Flis >> t >> s.apache.org%2Fthread.html%2F79aa6e50d7c737ddf83455dd8063692a535a1afa >> 5 >> 58620fe1a1496d3%40%253Cdev.kafka.apache.org%253E&data=02%7C01%7Cs >> e >> nthilm%40microsoft.com%7C686c32fa4a554d61ae1408d756d409f6%7C72f988bf8 >> 6 >> f141af91ab2d7cd011db47%7C1%7C0%7C637073341017520406&sdata=XwcUWWY >> D >> PV1nA%2BbkDGLFNlXZ5bysVblWUTDQEzAaKxM%3D&reserved=0 >> Previous Thread VOTE: >> https://nam06.safelinks.protection.outlook.com/?url=https%3A%2F%2Flis >> t >> s.apache.org%2Fthread.html%2Fb2ecd73ce849741f0c40b4f801c3f76505834978 >> 1 >> 2713e240e1ac2b7%40%253Cdev.kafka.apache.org%253E&data=02%7C01%7Cs >> e >> nthilm%40microsoft.com%7C686c32fa4a554d61ae1408d756d409f6%7C72f988bf8 >> 6 >> f141af91ab2d7cd011db47%7C1%7C0%7C637073341017520406&sdata=8cKQcAm >> 2 >> DDVGVLTKtciYKGMiI%2FgOADW6tam9nem4lsg%3D&reserved=0 >> >> Appreciate your timely action. >> >> PS: Initiating a separate thread as I was not able to reply to the >> existing threads... >> >> Thanks, >> Senthil >>
