Hi, Justine, Thanks for the update and sorry for the late reply.
120. I am wondering what value is used for ClientTransactionProtocolVersion. Is it the version of the EndTxnRequest? 121. Earlier, you made the change to set lastProducerId in PREPARE to indicate that the marker is written for the new client. With the new ClientTransactionProtocolVersion field, it seems this is no longer necessary. Jun On Thu, Mar 28, 2024 at 2:41 PM Justine Olshan <jols...@confluent.io.invalid> wrote: > Hi there -- another update! > > When looking into the implementation for the safe epoch bumps I realized > that we are already populating previousProducerID in memory as part of > KIP-360. > If we are to start using flexible fields, it is better to always use this > information and have an explicit (tagged) field to indicate whether the > client supports KIP-890 part 2. > > I've included the extra field and how it is set in the KIP. I've also > updated the KIP to explain that we will be setting the tagged fields when > they are available for all transitions. > > Finally, I added clearer text about the transaction protocol versions > included with this KIP. 1 for flexible transaction state records and 2 for > KIP-890 part 2 enablement. > > Justine > > On Mon, Mar 18, 2024 at 6:39 PM Justine Olshan <jols...@confluent.io> > wrote: > > > Hey there -- small update to the KIP, > > > > The KIP mentioned introducing ABORTABLE_ERROR and bumping TxnOffsetCommit > > and Produce requests. I've changed the name in the KIP to > > ABORTABLE_TRANSACTION and the corresponding exception > > AbortableTransactionException to match the pattern we had for other > errors. > > I also mentioned bumping all 6 transactional APIs so we can future > > proof/support the error on the client going forward. If a future change > > wants to have an error scenario that requires us to abort the > transaction, > > we can rely on the 3.8+ clients to support it. We ran into issues finding > > good/generic error codes that older clients could support while working > on > > this KIP, so this should help in the future. > > > > The features discussion is still ongoing in KIP-1022. Will update again > > here when that concludes. > > > > Justine > > > > On Tue, Feb 6, 2024 at 8:39 AM Justine Olshan <jols...@confluent.io> > > wrote: > > > >> I don't think AddPartitions is a good example since we currenly don't > >> gate the version on TV or MV. (We only set a different flag depending on > >> the TV) > >> > >> Even if we did want to gate it on TV, I think the idea is to move away > >> from MV gating inter broker protocols. Ideally we can get to a state > where > >> MV is just used for metadata changes. > >> > >> I think some of this discussion might fit more with the feature version > >> KIP, so I can try to open that up soon. Until we settle that, some of > the > >> work in KIP-890 is blocked. > >> > >> Justine > >> > >> On Mon, Feb 5, 2024 at 5:38 PM Jun Rao <j...@confluent.io.invalid> > wrote: > >> > >>> Hi, Justine, > >>> > >>> Thanks for the reply. > >>> > >>> Since AddPartitions is an inter broker request, will its version be > gated > >>> only by TV or other features like MV too? For example, if we need to > >>> change > >>> the protocol for AddPartitions for reasons other than txn verification > in > >>> the future, will the new version be gated by a new MV? If so, does > >>> downgrading a TV imply potential downgrade of MV too? > >>> > >>> Jun > >>> > >>> > >>> > >>> On Mon, Feb 5, 2024 at 5:07 PM Justine Olshan > >>> <jols...@confluent.io.invalid> > >>> wrote: > >>> > >>> > One TV gates the flexible feature version (no rpcs involved, only the > >>> > transactional records that should only be gated by TV) > >>> > Another TV gates the ability to turn on kip-890 part 2. This would > >>> gate the > >>> > version of Produce and EndTxn (likely only used by transactions), and > >>> > specifies a flag in AddPartitionsToTxn though the version is already > >>> used > >>> > without TV. > >>> > > >>> > I think the only concern is the Produce request and we could consider > >>> work > >>> > arounds similar to the AddPartitionsToTxn call. > >>> > > >>> > Justine > >>> > > >>> > On Mon, Feb 5, 2024 at 4:56 PM Jun Rao <j...@confluent.io.invalid> > >>> wrote: > >>> > > >>> > > Hi, Justine, > >>> > > > >>> > > Which PRC/record protocols will TV guard? Going forward, will those > >>> > > PRC/record protocols only be guarded by TV and not by other > features > >>> like > >>> > > MV? > >>> > > > >>> > > Thanks, > >>> > > > >>> > > Jun > >>> > > > >>> > > On Mon, Feb 5, 2024 at 2:41 PM Justine Olshan > >>> > <jols...@confluent.io.invalid > >>> > > > > >>> > > wrote: > >>> > > > >>> > > > Hi Jun, > >>> > > > > >>> > > > Sorry I think I misunderstood your question or answered > >>> incorrectly. > >>> > The > >>> > > TV > >>> > > > version should ideally be fully independent from MV. > >>> > > > At least for the changes I proposed, TV should not affect MV and > MV > >>> > > should > >>> > > > not affect TV/ > >>> > > > > >>> > > > I think if we downgrade TV, only that feature should downgrade. > >>> > Likewise > >>> > > > the same with MV. The finalizedFeatures should just reflect the > >>> feature > >>> > > > downgrade we made. > >>> > > > > >>> > > > I also plan to write a new KIP for managing the disk format and > >>> upgrade > >>> > > > tool as we will need new flags to support these features. That > >>> should > >>> > > help > >>> > > > clarify some things. > >>> > > > > >>> > > > Justine > >>> > > > > >>> > > > On Mon, Feb 5, 2024 at 11:03 AM Jun Rao <j...@confluent.io.invalid > > > >>> > > wrote: > >>> > > > > >>> > > > > Hi, Justine, > >>> > > > > > >>> > > > > Thanks for the reply. > >>> > > > > > >>> > > > > So, if we downgrade TV, we could implicitly downgrade another > >>> feature > >>> > > > (say > >>> > > > > MV) that has dependency (e.g. RPC). What would we return for > >>> > > > > FinalizedFeatures for MV in ApiVersionsResponse in that case? > >>> > > > > > >>> > > > > Thanks, > >>> > > > > > >>> > > > > Jun > >>> > > > > > >>> > > > > On Fri, Feb 2, 2024 at 1:06 PM Justine Olshan > >>> > > > <jols...@confluent.io.invalid > >>> > > > > > > >>> > > > > wrote: > >>> > > > > > >>> > > > > > Hey Jun, > >>> > > > > > > >>> > > > > > Yes, the idea is that if we downgrade TV (transaction > version) > >>> we > >>> > > will > >>> > > > > stop > >>> > > > > > using the add partitions to txn optimization and stop writing > >>> the > >>> > > > > flexible > >>> > > > > > feature version of the log. > >>> > > > > > In the compatibility section I included some explanations on > >>> how > >>> > this > >>> > > > is > >>> > > > > > done. > >>> > > > > > > >>> > > > > > Thanks, > >>> > > > > > Justine > >>> > > > > > > >>> > > > > > On Fri, Feb 2, 2024 at 11:12 AM Jun Rao > >>> <j...@confluent.io.invalid> > >>> > > > > wrote: > >>> > > > > > > >>> > > > > > > Hi, Justine, > >>> > > > > > > > >>> > > > > > > Thanks for the update. > >>> > > > > > > > >>> > > > > > > If we ever downgrade the transaction feature, any feature > >>> > depending > >>> > > > on > >>> > > > > > > changes on top of those RPC/record > >>> > > > > > > (AddPartitionsToTxnRequest/TransactionLogValue) changes > made > >>> in > >>> > > > KIP-890 > >>> > > > > > > will be automatically downgraded too? > >>> > > > > > > > >>> > > > > > > Jun > >>> > > > > > > > >>> > > > > > > On Tue, Jan 30, 2024 at 3:32 PM Justine Olshan > >>> > > > > > > <jols...@confluent.io.invalid> > >>> > > > > > > wrote: > >>> > > > > > > > >>> > > > > > > > Hey Jun, > >>> > > > > > > > > >>> > > > > > > > I wanted to get back to you about your questions about > >>> MV/IBP. > >>> > > > > > > > > >>> > > > > > > > Looking at the options, I think it makes the most sense > to > >>> > > create a > >>> > > > > > > > separate feature for transactions and use that to version > >>> gate > >>> > > the > >>> > > > > > > features > >>> > > > > > > > we need to version gate (flexible transactional state > >>> records > >>> > and > >>> > > > > using > >>> > > > > > > the > >>> > > > > > > > new protocol) > >>> > > > > > > > I've updated the KIP to include this change. Hopefully > >>> that's > >>> > > > > > everything > >>> > > > > > > we > >>> > > > > > > > need for this KIP :) > >>> > > > > > > > > >>> > > > > > > > Justine > >>> > > > > > > > > >>> > > > > > > > > >>> > > > > > > > On Mon, Jan 22, 2024 at 3:17 PM Justine Olshan < > >>> > > > jols...@confluent.io > >>> > > > > > > >>> > > > > > > > wrote: > >>> > > > > > > > > >>> > > > > > > > > Thanks Jun, > >>> > > > > > > > > > >>> > > > > > > > > I will update the KIP with the prev field for prepare > as > >>> > well. > >>> > > > > > > > > > >>> > > > > > > > > PREPARE > >>> > > > > > > > > producerId: x > >>> > > > > > > > > previous/lastProducerId (tagged field): x > >>> > > > > > > > > nextProducerId (tagged field): empty or z if y will > >>> overflow > >>> > > > > > > > > producerEpoch: y + 1 > >>> > > > > > > > > > >>> > > > > > > > > COMPLETE > >>> > > > > > > > > producerId: x or z if y overflowed > >>> > > > > > > > > previous/lastProducerId (tagged field): x > >>> > > > > > > > > nextProducerId (tagged field): empty > >>> > > > > > > > > producerEpoch: y + 1 or 0 if we overflowed > >>> > > > > > > > > > >>> > > > > > > > > Thanks again, > >>> > > > > > > > > Justine > >>> > > > > > > > > > >>> > > > > > > > > On Mon, Jan 22, 2024 at 3:15 PM Jun Rao > >>> > > <j...@confluent.io.invalid > >>> > > > > > >>> > > > > > > > wrote: > >>> > > > > > > > > > >>> > > > > > > > >> Hi, Justine, > >>> > > > > > > > >> > >>> > > > > > > > >> 101.3 Thanks for the explanation. > >>> > > > > > > > >> (1) My point was that the coordinator could fail right > >>> after > >>> > > > > writing > >>> > > > > > > the > >>> > > > > > > > >> prepare marker. When the new txn coordinator generates > >>> the > >>> > > > > complete > >>> > > > > > > > marker > >>> > > > > > > > >> after the failover, it needs some field from the > prepare > >>> > > marker > >>> > > > to > >>> > > > > > > > >> determine whether it's written by the new client. > >>> > > > > > > > >> > >>> > > > > > > > >> (2) The changing of the behavior sounds good to me. We > >>> only > >>> > > want > >>> > > > > to > >>> > > > > > > > return > >>> > > > > > > > >> success if the prepare state is written by the new > >>> client. > >>> > So, > >>> > > > in > >>> > > > > > the > >>> > > > > > > > >> non-overflow case, it seems that we also need sth in > the > >>> > > prepare > >>> > > > > > > marker > >>> > > > > > > > to > >>> > > > > > > > >> tell us whether it's written by the new client. > >>> > > > > > > > >> > >>> > > > > > > > >> 112. Thanks for the explanation. That sounds good to > me. > >>> > > > > > > > >> > >>> > > > > > > > >> Jun > >>> > > > > > > > >> > >>> > > > > > > > >> On Mon, Jan 22, 2024 at 11:32 AM Justine Olshan > >>> > > > > > > > >> <jols...@confluent.io.invalid> wrote: > >>> > > > > > > > >> > >>> > > > > > > > >> > 101.3 I realized that I actually have two questions. > >>> > > > > > > > >> > > (1) In the non-overflow case, we need to write the > >>> > > previous > >>> > > > > > > produce > >>> > > > > > > > Id > >>> > > > > > > > >> > tagged field in the end maker so that we know if the > >>> > marker > >>> > > is > >>> > > > > > from > >>> > > > > > > > the > >>> > > > > > > > >> new > >>> > > > > > > > >> > client. Since the end maker is derived from the > >>> prepare > >>> > > > marker, > >>> > > > > > > should > >>> > > > > > > > >> we > >>> > > > > > > > >> > write the previous produce Id in the prepare marker > >>> field > >>> > > too? > >>> > > > > > > > >> Otherwise, > >>> > > > > > > > >> > we will lose this information when deriving the end > >>> > marker. > >>> > > > > > > > >> > > >>> > > > > > > > >> > The "previous" producer ID is in the normal producer > >>> ID > >>> > > field. > >>> > > > > So > >>> > > > > > > yes, > >>> > > > > > > > >> we > >>> > > > > > > > >> > need it in prepare and that was always the plan. > >>> > > > > > > > >> > > >>> > > > > > > > >> > Maybe it is a bit unclear so I will enumerate the > >>> fields > >>> > and > >>> > > > add > >>> > > > > > > them > >>> > > > > > > > to > >>> > > > > > > > >> > the KIP if that helps. > >>> > > > > > > > >> > Say we have producer ID x and epoch y. When we > >>> overflow > >>> > > epoch > >>> > > > y > >>> > > > > we > >>> > > > > > > get > >>> > > > > > > > >> > producer ID Z. > >>> > > > > > > > >> > > >>> > > > > > > > >> > PREPARE > >>> > > > > > > > >> > producerId: x > >>> > > > > > > > >> > previous/lastProducerId (tagged field): empty > >>> > > > > > > > >> > nextProducerId (tagged field): empty or z if y will > >>> > overflow > >>> > > > > > > > >> > producerEpoch: y + 1 > >>> > > > > > > > >> > > >>> > > > > > > > >> > COMPLETE > >>> > > > > > > > >> > producerId: x or z if y overflowed > >>> > > > > > > > >> > previous/lastProducerId (tagged field): x > >>> > > > > > > > >> > nextProducerId (tagged field): empty > >>> > > > > > > > >> > producerEpoch: y + 1 or 0 if we overflowed > >>> > > > > > > > >> > > >>> > > > > > > > >> > (2) In the prepare phase, if we retry and see epoch > - > >>> 1 + > >>> > ID > >>> > > > in > >>> > > > > > last > >>> > > > > > > > >> seen > >>> > > > > > > > >> > fields and are issuing the same command (ie commit > not > >>> > > abort), > >>> > > > > we > >>> > > > > > > > return > >>> > > > > > > > >> > success. The logic before KIP-890 seems to return > >>> > > > > > > > >> CONCURRENT_TRANSACTIONS > >>> > > > > > > > >> > in this case. Are we intentionally making this > change? > >>> > > > > > > > >> > > >>> > > > > > > > >> > Hmm -- we would fence the producer if the epoch is > >>> bumped > >>> > > and > >>> > > > we > >>> > > > > > > get a > >>> > > > > > > > >> > lower epoch. Yes -- we are intentionally adding this > >>> to > >>> > > > prevent > >>> > > > > > > > fencing. > >>> > > > > > > > >> > > >>> > > > > > > > >> > > >>> > > > > > > > >> > 112. We already merged the code that adds the > >>> VerifyOnly > >>> > > field > >>> > > > > in > >>> > > > > > > > >> > AddPartitionsToTxnRequest, which is an inter broker > >>> > request. > >>> > > > It > >>> > > > > > > seems > >>> > > > > > > > >> that > >>> > > > > > > > >> > we didn't bump up the IBP for that. Do you know why? > >>> > > > > > > > >> > > >>> > > > > > > > >> > We no longer need IBP for all interbroker requests > as > >>> > > > > ApiVersions > >>> > > > > > > > should > >>> > > > > > > > >> > correctly gate versioning. > >>> > > > > > > > >> > We also handle unsupported version errors correctly > >>> if we > >>> > > > > receive > >>> > > > > > > them > >>> > > > > > > > >> in > >>> > > > > > > > >> > edge cases like upgrades/downgrades. > >>> > > > > > > > >> > > >>> > > > > > > > >> > Justine > >>> > > > > > > > >> > > >>> > > > > > > > >> > On Mon, Jan 22, 2024 at 11:00 AM Jun Rao > >>> > > > > <j...@confluent.io.invalid > >>> > > > > > > > >>> > > > > > > > >> wrote: > >>> > > > > > > > >> > > >>> > > > > > > > >> > > Hi, Justine, > >>> > > > > > > > >> > > > >>> > > > > > > > >> > > Thanks for the reply. > >>> > > > > > > > >> > > > >>> > > > > > > > >> > > 101.3 I realized that I actually have two > questions. > >>> > > > > > > > >> > > (1) In the non-overflow case, we need to write the > >>> > > previous > >>> > > > > > > produce > >>> > > > > > > > Id > >>> > > > > > > > >> > > tagged field in the end maker so that we know if > the > >>> > > marker > >>> > > > is > >>> > > > > > > from > >>> > > > > > > > >> the > >>> > > > > > > > >> > new > >>> > > > > > > > >> > > client. Since the end maker is derived from the > >>> prepare > >>> > > > > marker, > >>> > > > > > > > >> should we > >>> > > > > > > > >> > > write the previous produce Id in the prepare > marker > >>> > field > >>> > > > too? > >>> > > > > > > > >> Otherwise, > >>> > > > > > > > >> > > we will lose this information when deriving the > end > >>> > > marker. > >>> > > > > > > > >> > > (2) In the prepare phase, if we retry and see > epoch > >>> - 1 > >>> > + > >>> > > ID > >>> > > > > in > >>> > > > > > > last > >>> > > > > > > > >> seen > >>> > > > > > > > >> > > fields and are issuing the same command (ie commit > >>> not > >>> > > > abort), > >>> > > > > > we > >>> > > > > > > > >> return > >>> > > > > > > > >> > > success. The logic before KIP-890 seems to return > >>> > > > > > > > >> CONCURRENT_TRANSACTIONS > >>> > > > > > > > >> > > in this case. Are we intentionally making this > >>> change? > >>> > > > > > > > >> > > > >>> > > > > > > > >> > > 112. We already merged the code that adds the > >>> VerifyOnly > >>> > > > field > >>> > > > > > in > >>> > > > > > > > >> > > AddPartitionsToTxnRequest, which is an inter > broker > >>> > > request. > >>> > > > > It > >>> > > > > > > > seems > >>> > > > > > > > >> > that > >>> > > > > > > > >> > > we didn't bump up the IBP for that. Do you know > why? > >>> > > > > > > > >> > > > >>> > > > > > > > >> > > Jun > >>> > > > > > > > >> > > > >>> > > > > > > > >> > > On Fri, Jan 19, 2024 at 4:50 PM Justine Olshan > >>> > > > > > > > >> > > <jols...@confluent.io.invalid> > >>> > > > > > > > >> > > wrote: > >>> > > > > > > > >> > > > >>> > > > > > > > >> > > > Hi Jun, > >>> > > > > > > > >> > > > > >>> > > > > > > > >> > > > 101.3 I can change "last seen" to "current > >>> producer id > >>> > > and > >>> > > > > > > epoch" > >>> > > > > > > > if > >>> > > > > > > > >> > that > >>> > > > > > > > >> > > > was the part that was confusing > >>> > > > > > > > >> > > > 110 I can mention this > >>> > > > > > > > >> > > > 111 I can do that > >>> > > > > > > > >> > > > 112 We still need it. But I am still finalizing > >>> the > >>> > > > design. > >>> > > > > I > >>> > > > > > > will > >>> > > > > > > > >> > update > >>> > > > > > > > >> > > > the KIP once I get the information finalized. > >>> Sorry > >>> > for > >>> > > > the > >>> > > > > > > > delays. > >>> > > > > > > > >> > > > > >>> > > > > > > > >> > > > Justine > >>> > > > > > > > >> > > > > >>> > > > > > > > >> > > > On Fri, Jan 19, 2024 at 10:50 AM Jun Rao > >>> > > > > > > <j...@confluent.io.invalid > >>> > > > > > > > > > >>> > > > > > > > >> > > wrote: > >>> > > > > > > > >> > > > > >>> > > > > > > > >> > > > > Hi, Justine, > >>> > > > > > > > >> > > > > > >>> > > > > > > > >> > > > > Thanks for the reply. > >>> > > > > > > > >> > > > > > >>> > > > > > > > >> > > > > 101.3 In the non-overflow case, the previous > ID > >>> is > >>> > the > >>> > > > > same > >>> > > > > > as > >>> > > > > > > > the > >>> > > > > > > > >> > > > produce > >>> > > > > > > > >> > > > > ID for the complete marker too, but we set the > >>> > > previous > >>> > > > ID > >>> > > > > > in > >>> > > > > > > > the > >>> > > > > > > > >> > > > complete > >>> > > > > > > > >> > > > > marker. Earlier you mentioned that this is to > >>> know > >>> > > that > >>> > > > > the > >>> > > > > > > > >> marker is > >>> > > > > > > > >> > > > > written by the new client so that we could > >>> return > >>> > > > success > >>> > > > > on > >>> > > > > > > > >> retried > >>> > > > > > > > >> > > > > endMarker requests. I was trying to understand > >>> why > >>> > > this > >>> > > > is > >>> > > > > > not > >>> > > > > > > > >> needed > >>> > > > > > > > >> > > for > >>> > > > > > > > >> > > > > the prepare marker since retry can happen in > the > >>> > > prepare > >>> > > > > > state > >>> > > > > > > > >> too. > >>> > > > > > > > >> > Is > >>> > > > > > > > >> > > > the > >>> > > > > > > > >> > > > > reason that in the prepare state, we return > >>> > > > > > > > >> CONCURRENT_TRANSACTIONS > >>> > > > > > > > >> > > > instead > >>> > > > > > > > >> > > > > of success on retried endMaker requests? If > so, > >>> > should > >>> > > > we > >>> > > > > > > change > >>> > > > > > > > >> "If > >>> > > > > > > > >> > we > >>> > > > > > > > >> > > > > retry and see epoch - 1 + ID in last seen > >>> fields and > >>> > > are > >>> > > > > > > issuing > >>> > > > > > > > >> the > >>> > > > > > > > >> > > same > >>> > > > > > > > >> > > > > command (ie commit not abort) we can return > >>> (with > >>> > the > >>> > > > new > >>> > > > > > > > epoch)" > >>> > > > > > > > >> > > > > accordingly? > >>> > > > > > > > >> > > > > > >>> > > > > > > > >> > > > > 110. Yes, without this KIP, a delayed endMaker > >>> > request > >>> > > > > > carries > >>> > > > > > > > the > >>> > > > > > > > >> > same > >>> > > > > > > > >> > > > > epoch and won't be fenced. This can > >>> commit/abort a > >>> > > > future > >>> > > > > > > > >> transaction > >>> > > > > > > > >> > > > > unexpectedly. I am not sure if we have seen > >>> this in > >>> > > > > practice > >>> > > > > > > > >> though. > >>> > > > > > > > >> > > > > > >>> > > > > > > > >> > > > > 111. Sounds good. It would be useful to make > it > >>> > clear > >>> > > > that > >>> > > > > > we > >>> > > > > > > > can > >>> > > > > > > > >> now > >>> > > > > > > > >> > > > > populate the lastSeen field from the log > >>> reliably. > >>> > > > > > > > >> > > > > > >>> > > > > > > > >> > > > > 112. Yes, I was referring to > >>> > AddPartitionsToTxnRequest > >>> > > > > since > >>> > > > > > > > it's > >>> > > > > > > > >> > > called > >>> > > > > > > > >> > > > > across brokers and we are changing its schema. > >>> Are > >>> > you > >>> > > > > > saying > >>> > > > > > > we > >>> > > > > > > > >> > don't > >>> > > > > > > > >> > > > need > >>> > > > > > > > >> > > > > it any more? I thought that we already > >>> implemented > >>> > the > >>> > > > > > server > >>> > > > > > > > side > >>> > > > > > > > >> > > > > verification logic based on > >>> > AddPartitionsToTxnRequest > >>> > > > > across > >>> > > > > > > > >> brokers. > >>> > > > > > > > >> > > > > > >>> > > > > > > > >> > > > > Jun > >>> > > > > > > > >> > > > > > >>> > > > > > > > >> > > > > > >>> > > > > > > > >> > > > > On Thu, Jan 18, 2024 at 5:05 PM Justine Olshan > >>> > > > > > > > >> > > > > <jols...@confluent.io.invalid> > >>> > > > > > > > >> > > > > wrote: > >>> > > > > > > > >> > > > > > >>> > > > > > > > >> > > > > > Hey Jun, > >>> > > > > > > > >> > > > > > > >>> > > > > > > > >> > > > > > 101.3 We don't set the previous ID in the > >>> Prepare > >>> > > > field > >>> > > > > > > since > >>> > > > > > > > we > >>> > > > > > > > >> > > don't > >>> > > > > > > > >> > > > > need > >>> > > > > > > > >> > > > > > it. It is the same producer ID as the main > >>> > producer > >>> > > ID > >>> > > > > > > field. > >>> > > > > > > > >> > > > > > > >>> > > > > > > > >> > > > > > 110 Hmm -- maybe I need to reread your > message > >>> > about > >>> > > > > > delayed > >>> > > > > > > > >> > markers. > >>> > > > > > > > >> > > > If > >>> > > > > > > > >> > > > > we > >>> > > > > > > > >> > > > > > receive a delayed endTxn marker after the > >>> > > transaction > >>> > > > is > >>> > > > > > > > already > >>> > > > > > > > >> > > > > complete? > >>> > > > > > > > >> > > > > > So we will commit the next transaction early > >>> > without > >>> > > > the > >>> > > > > > > fixes > >>> > > > > > > > >> in > >>> > > > > > > > >> > > part > >>> > > > > > > > >> > > > 2? > >>> > > > > > > > >> > > > > > > >>> > > > > > > > >> > > > > > 111 Yes -- this terminology was used in a > >>> previous > >>> > > KIP > >>> > > > > and > >>> > > > > > > > never > >>> > > > > > > > >> > > > > > implemented it in the log -- only in memory > >>> > > > > > > > >> > > > > > > >>> > > > > > > > >> > > > > > 112 Hmm -- which interbroker protocol are > you > >>> > > > referring > >>> > > > > > to? > >>> > > > > > > I > >>> > > > > > > > am > >>> > > > > > > > >> > > > working > >>> > > > > > > > >> > > > > on > >>> > > > > > > > >> > > > > > the design for the work to remove the extra > >>> add > >>> > > > > partitions > >>> > > > > > > > call > >>> > > > > > > > >> > and I > >>> > > > > > > > >> > > > > right > >>> > > > > > > > >> > > > > > now the design bumps MV. I have yet to > update > >>> that > >>> > > > > section > >>> > > > > > > as > >>> > > > > > > > I > >>> > > > > > > > >> > > > finalize > >>> > > > > > > > >> > > > > > the design so please stay tuned. Was there > >>> > anything > >>> > > > else > >>> > > > > > you > >>> > > > > > > > >> > thought > >>> > > > > > > > >> > > > > needed > >>> > > > > > > > >> > > > > > MV bump? > >>> > > > > > > > >> > > > > > > >>> > > > > > > > >> > > > > > Justine > >>> > > > > > > > >> > > > > > > >>> > > > > > > > >> > > > > > On Thu, Jan 18, 2024 at 3:07 PM Jun Rao > >>> > > > > > > > >> <j...@confluent.io.invalid> > >>> > > > > > > > >> > > > > wrote: > >>> > > > > > > > >> > > > > > > >>> > > > > > > > >> > > > > > > Hi, Justine, > >>> > > > > > > > >> > > > > > > > >>> > > > > > > > >> > > > > > > I don't see this create any issue. It just > >>> makes > >>> > > it > >>> > > > a > >>> > > > > > bit > >>> > > > > > > > >> hard to > >>> > > > > > > > >> > > > > explain > >>> > > > > > > > >> > > > > > > what this non-tagged produce id field > >>> means. We > >>> > > are > >>> > > > > > > > >> essentially > >>> > > > > > > > >> > > > trying > >>> > > > > > > > >> > > > > to > >>> > > > > > > > >> > > > > > > combine two actions (completing a txn and > >>> init a > >>> > > new > >>> > > > > > > produce > >>> > > > > > > > >> Id) > >>> > > > > > > > >> > > in a > >>> > > > > > > > >> > > > > > > single record. But, this may be fine too. > >>> > > > > > > > >> > > > > > > > >>> > > > > > > > >> > > > > > > A few other follow up comments. > >>> > > > > > > > >> > > > > > > > >>> > > > > > > > >> > > > > > > 101.3 I guess the reason that we only set > >>> the > >>> > > > previous > >>> > > > > > > > >> produce id > >>> > > > > > > > >> > > > > tagged > >>> > > > > > > > >> > > > > > > field in the complete marker, but not in > the > >>> > > prepare > >>> > > > > > > marker, > >>> > > > > > > > >> is > >>> > > > > > > > >> > > that > >>> > > > > > > > >> > > > in > >>> > > > > > > > >> > > > > > the > >>> > > > > > > > >> > > > > > > prepare state, we always return > >>> > > > > CONCURRENT_TRANSACTIONS > >>> > > > > > on > >>> > > > > > > > >> > retried > >>> > > > > > > > >> > > > > > endMaker > >>> > > > > > > > >> > > > > > > requests? > >>> > > > > > > > >> > > > > > > > >>> > > > > > > > >> > > > > > > 110. "I believe your second point is > >>> mentioned > >>> > in > >>> > > > the > >>> > > > > > > KIP. I > >>> > > > > > > > >> can > >>> > > > > > > > >> > > add > >>> > > > > > > > >> > > > > more > >>> > > > > > > > >> > > > > > > text on > >>> > > > > > > > >> > > > > > > this if it is helpful. > >>> > > > > > > > >> > > > > > > > The delayed message case can also > violate > >>> EOS > >>> > if > >>> > > > the > >>> > > > > > > > delayed > >>> > > > > > > > >> > > > message > >>> > > > > > > > >> > > > > > > comes in after the next addPartitionsToTxn > >>> > request > >>> > > > > comes > >>> > > > > > > in. > >>> > > > > > > > >> > > > > Effectively > >>> > > > > > > > >> > > > > > we > >>> > > > > > > > >> > > > > > > may see a message from a previous > (aborted) > >>> > > > > transaction > >>> > > > > > > > become > >>> > > > > > > > >> > part > >>> > > > > > > > >> > > > of > >>> > > > > > > > >> > > > > > the > >>> > > > > > > > >> > > > > > > next transaction." > >>> > > > > > > > >> > > > > > > > >>> > > > > > > > >> > > > > > > The above is the case when a delayed > >>> message is > >>> > > > > appended > >>> > > > > > > to > >>> > > > > > > > >> the > >>> > > > > > > > >> > > data > >>> > > > > > > > >> > > > > > > partition. What I mentioned is a slightly > >>> > > different > >>> > > > > case > >>> > > > > > > > when > >>> > > > > > > > >> a > >>> > > > > > > > >> > > > delayed > >>> > > > > > > > >> > > > > > > marker is appended to the transaction log > >>> > > partition. > >>> > > > > > > > >> > > > > > > > >>> > > > > > > > >> > > > > > > 111. The KIP says "Once we move past the > >>> Prepare > >>> > > and > >>> > > > > > > > Complete > >>> > > > > > > > >> > > states, > >>> > > > > > > > >> > > > > we > >>> > > > > > > > >> > > > > > > don’t need to worry about lastSeen fields > >>> and > >>> > > clear > >>> > > > > > them, > >>> > > > > > > > just > >>> > > > > > > > >> > > handle > >>> > > > > > > > >> > > > > > state > >>> > > > > > > > >> > > > > > > transitions as normal.". Is the lastSeen > >>> field > >>> > the > >>> > > > > same > >>> > > > > > as > >>> > > > > > > > the > >>> > > > > > > > >> > > > previous > >>> > > > > > > > >> > > > > > > Produce Id tagged field in > >>> TransactionLogValue? > >>> > > > > > > > >> > > > > > > > >>> > > > > > > > >> > > > > > > 112. Since the kip changes the > inter-broker > >>> > > > protocol, > >>> > > > > > > should > >>> > > > > > > > >> we > >>> > > > > > > > >> > > bump > >>> > > > > > > > >> > > > up > >>> > > > > > > > >> > > > > > the > >>> > > > > > > > >> > > > > > > MV/IBP version? Is this feature only for > the > >>> > KRaft > >>> > > > > mode? > >>> > > > > > > > >> > > > > > > > >>> > > > > > > > >> > > > > > > Thanks, > >>> > > > > > > > >> > > > > > > > >>> > > > > > > > >> > > > > > > Jun > >>> > > > > > > > >> > > > > > > > >>> > > > > > > > >> > > > > > > > >>> > > > > > > > >> > > > > > > On Wed, Jan 17, 2024 at 11:13 AM Justine > >>> Olshan > >>> > > > > > > > >> > > > > > > <jols...@confluent.io.invalid> wrote: > >>> > > > > > > > >> > > > > > > > >>> > > > > > > > >> > > > > > > > Hey Jun, > >>> > > > > > > > >> > > > > > > > > >>> > > > > > > > >> > > > > > > > I'm glad we are getting to convergence > on > >>> the > >>> > > > > design. > >>> > > > > > :) > >>> > > > > > > > >> > > > > > > > > >>> > > > > > > > >> > > > > > > > While I understand it seems a little > >>> "weird". > >>> > > I'm > >>> > > > > not > >>> > > > > > > sure > >>> > > > > > > > >> what > >>> > > > > > > > >> > > the > >>> > > > > > > > >> > > > > > > benefit > >>> > > > > > > > >> > > > > > > > of writing an extra record to the log. > >>> > > > > > > > >> > > > > > > > Is the concern a tool to describe > >>> transactions > >>> > > > won't > >>> > > > > > > work > >>> > > > > > > > >> (ie, > >>> > > > > > > > >> > > the > >>> > > > > > > > >> > > > > > > complete > >>> > > > > > > > >> > > > > > > > state is needed to calculate the time > >>> since > >>> > the > >>> > > > > > > > transaction > >>> > > > > > > > >> > > > > completed?) > >>> > > > > > > > >> > > > > > > > If we have a reason like this, it is > >>> enough to > >>> > > > > > convince > >>> > > > > > > me > >>> > > > > > > > >> we > >>> > > > > > > > >> > > need > >>> > > > > > > > >> > > > > such > >>> > > > > > > > >> > > > > > > an > >>> > > > > > > > >> > > > > > > > extra record. It seems like it would be > >>> > > replacing > >>> > > > > the > >>> > > > > > > > record > >>> > > > > > > > >> > > > written > >>> > > > > > > > >> > > > > on > >>> > > > > > > > >> > > > > > > > InitProducerId. Is this correct? > >>> > > > > > > > >> > > > > > > > > >>> > > > > > > > >> > > > > > > > Thanks, > >>> > > > > > > > >> > > > > > > > Justine > >>> > > > > > > > >> > > > > > > > > >>> > > > > > > > >> > > > > > > > On Tue, Jan 16, 2024 at 5:14 PM Jun Rao > >>> > > > > > > > >> > <j...@confluent.io.invalid > >>> > > > > > > > >> > > > > >>> > > > > > > > >> > > > > > > wrote: > >>> > > > > > > > >> > > > > > > > > >>> > > > > > > > >> > > > > > > > > Hi, Justine, > >>> > > > > > > > >> > > > > > > > > > >>> > > > > > > > >> > > > > > > > > Thanks for the explanation. I > >>> understand the > >>> > > > > > intention > >>> > > > > > > > >> now. > >>> > > > > > > > >> > In > >>> > > > > > > > >> > > > the > >>> > > > > > > > >> > > > > > > > overflow > >>> > > > > > > > >> > > > > > > > > case, we set the non-tagged field to > >>> the old > >>> > > pid > >>> > > > > > (and > >>> > > > > > > > the > >>> > > > > > > > >> max > >>> > > > > > > > >> > > > > epoch) > >>> > > > > > > > >> > > > > > in > >>> > > > > > > > >> > > > > > > > the > >>> > > > > > > > >> > > > > > > > > prepare marker so that we could > >>> correctly > >>> > > write > >>> > > > > the > >>> > > > > > > > >> marker to > >>> > > > > > > > >> > > the > >>> > > > > > > > >> > > > > > data > >>> > > > > > > > >> > > > > > > > > partition if the broker downgrades. > When > >>> > > writing > >>> > > > > the > >>> > > > > > > > >> complete > >>> > > > > > > > >> > > > > marker, > >>> > > > > > > > >> > > > > > > we > >>> > > > > > > > >> > > > > > > > > know the marker has already been > >>> written to > >>> > > the > >>> > > > > data > >>> > > > > > > > >> > partition. > >>> > > > > > > > >> > > > We > >>> > > > > > > > >> > > > > > set > >>> > > > > > > > >> > > > > > > > the > >>> > > > > > > > >> > > > > > > > > non-tagged field to the new pid to > avoid > >>> > > > > > > > >> > > > InvalidPidMappingException > >>> > > > > > > > >> > > > > > in > >>> > > > > > > > >> > > > > > > > the > >>> > > > > > > > >> > > > > > > > > client if the broker downgrades. > >>> > > > > > > > >> > > > > > > > > > >>> > > > > > > > >> > > > > > > > > The above seems to work. It's just a > bit > >>> > > > > > inconsistent > >>> > > > > > > > for > >>> > > > > > > > >> a > >>> > > > > > > > >> > > > prepare > >>> > > > > > > > >> > > > > > > > marker > >>> > > > > > > > >> > > > > > > > > and a complete marker to use different > >>> pids > >>> > in > >>> > > > > this > >>> > > > > > > > >> special > >>> > > > > > > > >> > > case. > >>> > > > > > > > >> > > > > If > >>> > > > > > > > >> > > > > > we > >>> > > > > > > > >> > > > > > > > > downgrade with the complete marker, it > >>> seems > >>> > > > that > >>> > > > > we > >>> > > > > > > > will > >>> > > > > > > > >> > never > >>> > > > > > > > >> > > > be > >>> > > > > > > > >> > > > > > able > >>> > > > > > > > >> > > > > > > > to > >>> > > > > > > > >> > > > > > > > > write the complete marker with the old > >>> pid. > >>> > > Not > >>> > > > > sure > >>> > > > > > > if > >>> > > > > > > > it > >>> > > > > > > > >> > > causes > >>> > > > > > > > >> > > > > any > >>> > > > > > > > >> > > > > > > > > issue, but it seems a bit weird. > >>> Instead of > >>> > > > > writing > >>> > > > > > > the > >>> > > > > > > > >> > > complete > >>> > > > > > > > >> > > > > > marker > >>> > > > > > > > >> > > > > > > > > with the new pid, could we write two > >>> > records: > >>> > > a > >>> > > > > > > complete > >>> > > > > > > > >> > marker > >>> > > > > > > > >> > > > > with > >>> > > > > > > > >> > > > > > > the > >>> > > > > > > > >> > > > > > > > > old pid followed by a > >>> TransactionLogValue > >>> > with > >>> > > > the > >>> > > > > > new > >>> > > > > > > > pid > >>> > > > > > > > >> > and > >>> > > > > > > > >> > > an > >>> > > > > > > > >> > > > > > empty > >>> > > > > > > > >> > > > > > > > > state? We could make the two records > in > >>> the > >>> > > same > >>> > > > > > batch > >>> > > > > > > > so > >>> > > > > > > > >> > that > >>> > > > > > > > >> > > > they > >>> > > > > > > > >> > > > > > > will > >>> > > > > > > > >> > > > > > > > be > >>> > > > > > > > >> > > > > > > > > added to the log atomically. > >>> > > > > > > > >> > > > > > > > > > >>> > > > > > > > >> > > > > > > > > Thanks, > >>> > > > > > > > >> > > > > > > > > > >>> > > > > > > > >> > > > > > > > > Jun > >>> > > > > > > > >> > > > > > > > > > >>> > > > > > > > >> > > > > > > > > > >>> > > > > > > > >> > > > > > > > > On Fri, Jan 12, 2024 at 5:40 PM > Justine > >>> > Olshan > >>> > > > > > > > >> > > > > > > > > <jols...@confluent.io.invalid> > >>> > > > > > > > >> > > > > > > > > wrote: > >>> > > > > > > > >> > > > > > > > > > >>> > > > > > > > >> > > > > > > > > > (1) the prepare marker is written, > >>> but the > >>> > > > > endTxn > >>> > > > > > > > >> response > >>> > > > > > > > >> > is > >>> > > > > > > > >> > > > not > >>> > > > > > > > >> > > > > > > > > received > >>> > > > > > > > >> > > > > > > > > > by the client when the server > >>> downgrades > >>> > > > > > > > >> > > > > > > > > > (2) the prepare marker is written, > >>> the > >>> > > endTxn > >>> > > > > > > > response > >>> > > > > > > > >> is > >>> > > > > > > > >> > > > > received > >>> > > > > > > > >> > > > > > > by > >>> > > > > > > > >> > > > > > > > > the > >>> > > > > > > > >> > > > > > > > > > client when the server downgrades. > >>> > > > > > > > >> > > > > > > > > > > >>> > > > > > > > >> > > > > > > > > > I think I am still a little > confused. > >>> In > >>> > > both > >>> > > > of > >>> > > > > > > these > >>> > > > > > > > >> > cases, > >>> > > > > > > > >> > > > the > >>> > > > > > > > >> > > > > > > > > > transaction log has the old producer > >>> ID. > >>> > We > >>> > > > > don't > >>> > > > > > > > write > >>> > > > > > > > >> the > >>> > > > > > > > >> > > new > >>> > > > > > > > >> > > > > > > > producer > >>> > > > > > > > >> > > > > > > > > ID > >>> > > > > > > > >> > > > > > > > > > in the prepare marker's non tagged > >>> fields. > >>> > > > > > > > >> > > > > > > > > > If the server downgrades now, it > would > >>> > read > >>> > > > the > >>> > > > > > > > records > >>> > > > > > > > >> not > >>> > > > > > > > >> > > in > >>> > > > > > > > >> > > > > > tagged > >>> > > > > > > > >> > > > > > > > > > fields and the complete marker will > >>> also > >>> > > have > >>> > > > > the > >>> > > > > > > old > >>> > > > > > > > >> > > producer > >>> > > > > > > > >> > > > > ID. > >>> > > > > > > > >> > > > > > > > > > (If we had used the new producer ID, > >>> we > >>> > > would > >>> > > > > not > >>> > > > > > > have > >>> > > > > > > > >> > > > > > transactional > >>> > > > > > > > >> > > > > > > > > > correctness since the producer id > >>> doesn't > >>> > > > match > >>> > > > > > the > >>> > > > > > > > >> > > transaction > >>> > > > > > > > >> > > > > and > >>> > > > > > > > >> > > > > > > the > >>> > > > > > > > >> > > > > > > > > > state would not be correct on the > data > >>> > > > > partition.) > >>> > > > > > > > >> > > > > > > > > > > >>> > > > > > > > >> > > > > > > > > > In the overflow case, I'd expect the > >>> > > following > >>> > > > > to > >>> > > > > > > > >> happen on > >>> > > > > > > > >> > > the > >>> > > > > > > > >> > > > > > > client > >>> > > > > > > > >> > > > > > > > > side > >>> > > > > > > > >> > > > > > > > > > Case 1 -- we retry EndTxn -- it is > >>> the > >>> > same > >>> > > > > > > producer > >>> > > > > > > > ID > >>> > > > > > > > >> > and > >>> > > > > > > > >> > > > > epoch > >>> > > > > > > > >> > > > > > - > >>> > > > > > > > >> > > > > > > 1 > >>> > > > > > > > >> > > > > > > > > this > >>> > > > > > > > >> > > > > > > > > > would fence the producer > >>> > > > > > > > >> > > > > > > > > > Case 2 -- we don't retry EndTxn and > >>> use > >>> > the > >>> > > > new > >>> > > > > > > > >> producer id > >>> > > > > > > > >> > > > which > >>> > > > > > > > >> > > > > > > would > >>> > > > > > > > >> > > > > > > > > > result in InvalidPidMappingException > >>> > > > > > > > >> > > > > > > > > > > >>> > > > > > > > >> > > > > > > > > > Maybe we can have special handling > for > >>> > when > >>> > > a > >>> > > > > > server > >>> > > > > > > > >> > > > downgrades. > >>> > > > > > > > >> > > > > > When > >>> > > > > > > > >> > > > > > > > it > >>> > > > > > > > >> > > > > > > > > > reconnects we could get an API > version > >>> > > request > >>> > > > > > > showing > >>> > > > > > > > >> > > KIP-890 > >>> > > > > > > > >> > > > > > part 2 > >>> > > > > > > > >> > > > > > > > is > >>> > > > > > > > >> > > > > > > > > > not supported. In that case, we can > >>> call > >>> > > > > > > > initProducerId > >>> > > > > > > > >> to > >>> > > > > > > > >> > > > abort > >>> > > > > > > > >> > > > > > the > >>> > > > > > > > >> > > > > > > > > > transaction. (In the overflow case, > >>> this > >>> > > > > correctly > >>> > > > > > > > gives > >>> > > > > > > > >> > us a > >>> > > > > > > > >> > > > new > >>> > > > > > > > >> > > > > > > > > producer > >>> > > > > > > > >> > > > > > > > > > ID) > >>> > > > > > > > >> > > > > > > > > > > >>> > > > > > > > >> > > > > > > > > > I guess the corresponding case would > >>> be > >>> > > where > >>> > > > > the > >>> > > > > > > > >> *complete > >>> > > > > > > > >> > > > > marker > >>> > > > > > > > >> > > > > > > *is > >>> > > > > > > > >> > > > > > > > > > written but the endTxn is not > >>> received by > >>> > > the > >>> > > > > > client > >>> > > > > > > > and > >>> > > > > > > > >> > the > >>> > > > > > > > >> > > > > server > >>> > > > > > > > >> > > > > > > > > > downgrades? This would result in the > >>> > > > transaction > >>> > > > > > > > >> > coordinator > >>> > > > > > > > >> > > > > having > >>> > > > > > > > >> > > > > > > the > >>> > > > > > > > >> > > > > > > > > new > >>> > > > > > > > >> > > > > > > > > > ID and not the old one. If the > client > >>> > > > retries, > >>> > > > > it > >>> > > > > > > > will > >>> > > > > > > > >> > > receive > >>> > > > > > > > >> > > > > an > >>> > > > > > > > >> > > > > > > > > > InvalidPidMappingException. The > >>> > > InitProducerId > >>> > > > > > > > scenario > >>> > > > > > > > >> > above > >>> > > > > > > > >> > > > > would > >>> > > > > > > > >> > > > > > > > help > >>> > > > > > > > >> > > > > > > > > > here too. > >>> > > > > > > > >> > > > > > > > > > > >>> > > > > > > > >> > > > > > > > > > To be clear, my compatibility story > is > >>> > meant > >>> > > > to > >>> > > > > > > > support > >>> > > > > > > > >> > > > > downgrades > >>> > > > > > > > >> > > > > > > > server > >>> > > > > > > > >> > > > > > > > > > side in keeping the transactional > >>> > > correctness. > >>> > > > > > > Keeping > >>> > > > > > > > >> the > >>> > > > > > > > >> > > > client > >>> > > > > > > > >> > > > > > > from > >>> > > > > > > > >> > > > > > > > > > fencing itself is not the priority. > >>> > > > > > > > >> > > > > > > > > > > >>> > > > > > > > >> > > > > > > > > > Hope this helps. I can also add text > >>> in > >>> > the > >>> > > > KIP > >>> > > > > > > about > >>> > > > > > > > >> > > > > > InitProducerId > >>> > > > > > > > >> > > > > > > if > >>> > > > > > > > >> > > > > > > > > we > >>> > > > > > > > >> > > > > > > > > > think that fixes some edge cases. > >>> > > > > > > > >> > > > > > > > > > > >>> > > > > > > > >> > > > > > > > > > Justine > >>> > > > > > > > >> > > > > > > > > > > >>> > > > > > > > >> > > > > > > > > > On Fri, Jan 12, 2024 at 4:10 PM Jun > >>> Rao > >>> > > > > > > > >> > > > <j...@confluent.io.invalid > >>> > > > > > > > >> > > > > > > >>> > > > > > > > >> > > > > > > > > wrote: > >>> > > > > > > > >> > > > > > > > > > > >>> > > > > > > > >> > > > > > > > > > > Hi, Justine, > >>> > > > > > > > >> > > > > > > > > > > > >>> > > > > > > > >> > > > > > > > > > > Thanks for the reply. > >>> > > > > > > > >> > > > > > > > > > > > >>> > > > > > > > >> > > > > > > > > > > I agree that we don't need to > >>> optimize > >>> > for > >>> > > > > > fencing > >>> > > > > > > > >> during > >>> > > > > > > > >> > > > > > > downgrades. > >>> > > > > > > > >> > > > > > > > > > > Regarding consistency, there are > two > >>> > > > possible > >>> > > > > > > cases: > >>> > > > > > > > >> (1) > >>> > > > > > > > >> > > the > >>> > > > > > > > >> > > > > > > prepare > >>> > > > > > > > >> > > > > > > > > > marker > >>> > > > > > > > >> > > > > > > > > > > is written, but the endTxn > response > >>> is > >>> > not > >>> > > > > > > received > >>> > > > > > > > by > >>> > > > > > > > >> > the > >>> > > > > > > > >> > > > > client > >>> > > > > > > > >> > > > > > > > when > >>> > > > > > > > >> > > > > > > > > > the > >>> > > > > > > > >> > > > > > > > > > > server downgrades; (2) the > prepare > >>> > marker > >>> > > > is > >>> > > > > > > > written, > >>> > > > > > > > >> > the > >>> > > > > > > > >> > > > > endTxn > >>> > > > > > > > >> > > > > > > > > > response > >>> > > > > > > > >> > > > > > > > > > > is received by the client when the > >>> > server > >>> > > > > > > > downgrades. > >>> > > > > > > > >> In > >>> > > > > > > > >> > > (1), > >>> > > > > > > > >> > > > > the > >>> > > > > > > > >> > > > > > > > > client > >>> > > > > > > > >> > > > > > > > > > > will have the old produce Id and > in > >>> (2), > >>> > > the > >>> > > > > > > client > >>> > > > > > > > >> will > >>> > > > > > > > >> > > have > >>> > > > > > > > >> > > > > the > >>> > > > > > > > >> > > > > > > new > >>> > > > > > > > >> > > > > > > > > > > produce Id. If we downgrade right > >>> after > >>> > > the > >>> > > > > > > prepare > >>> > > > > > > > >> > marker, > >>> > > > > > > > >> > > > we > >>> > > > > > > > >> > > > > > > can't > >>> > > > > > > > >> > > > > > > > be > >>> > > > > > > > >> > > > > > > > > > > consistent to both (1) and (2) > >>> since we > >>> > > can > >>> > > > > only > >>> > > > > > > put > >>> > > > > > > > >> one > >>> > > > > > > > >> > > > value > >>> > > > > > > > >> > > > > in > >>> > > > > > > > >> > > > > > > the > >>> > > > > > > > >> > > > > > > > > > > existing produce Id field. It's > >>> also not > >>> > > > clear > >>> > > > > > > which > >>> > > > > > > > >> case > >>> > > > > > > > >> > > is > >>> > > > > > > > >> > > > > more > >>> > > > > > > > >> > > > > > > > > likely. > >>> > > > > > > > >> > > > > > > > > > > So we could probably be consistent > >>> with > >>> > > > either > >>> > > > > > > case. > >>> > > > > > > > >> By > >>> > > > > > > > >> > > > putting > >>> > > > > > > > >> > > > > > the > >>> > > > > > > > >> > > > > > > > new > >>> > > > > > > > >> > > > > > > > > > > producer Id in the prepare marker, > >>> we > >>> > are > >>> > > > > > > consistent > >>> > > > > > > > >> with > >>> > > > > > > > >> > > > case > >>> > > > > > > > >> > > > > > (2) > >>> > > > > > > > >> > > > > > > > and > >>> > > > > > > > >> > > > > > > > > it > >>> > > > > > > > >> > > > > > > > > > > also has the slight benefit that > the > >>> > > produce > >>> > > > > > field > >>> > > > > > > > in > >>> > > > > > > > >> the > >>> > > > > > > > >> > > > > prepare > >>> > > > > > > > >> > > > > > > and > >>> > > > > > > > >> > > > > > > > > > > complete marker are consistent in > >>> the > >>> > > > overflow > >>> > > > > > > case. > >>> > > > > > > > >> > > > > > > > > > > > >>> > > > > > > > >> > > > > > > > > > > Jun > >>> > > > > > > > >> > > > > > > > > > > > >>> > > > > > > > >> > > > > > > > > > > On Fri, Jan 12, 2024 at 3:11 PM > >>> Justine > >>> > > > Olshan > >>> > > > > > > > >> > > > > > > > > > > <jols...@confluent.io.invalid> > >>> > > > > > > > >> > > > > > > > > > > wrote: > >>> > > > > > > > >> > > > > > > > > > > > >>> > > > > > > > >> > > > > > > > > > > > Hi Jun, > >>> > > > > > > > >> > > > > > > > > > > > > >>> > > > > > > > >> > > > > > > > > > > > In the case you describe, we > would > >>> > need > >>> > > to > >>> > > > > > have > >>> > > > > > > a > >>> > > > > > > > >> > delayed > >>> > > > > > > > >> > > > > > > request, > >>> > > > > > > > >> > > > > > > > > > send a > >>> > > > > > > > >> > > > > > > > > > > > successful EndTxn, and a > >>> successful > >>> > > > > > > > >> AddPartitionsToTxn > >>> > > > > > > > >> > > and > >>> > > > > > > > >> > > > > then > >>> > > > > > > > >> > > > > > > > have > >>> > > > > > > > >> > > > > > > > > > the > >>> > > > > > > > >> > > > > > > > > > > > delayed EndTxn request go > through > >>> for > >>> > a > >>> > > > > given > >>> > > > > > > > >> producer. > >>> > > > > > > > >> > > > > > > > > > > > I'm trying to figure out if it > is > >>> > > possible > >>> > > > > for > >>> > > > > > > the > >>> > > > > > > > >> > client > >>> > > > > > > > >> > > > to > >>> > > > > > > > >> > > > > > > > > transition > >>> > > > > > > > >> > > > > > > > > > > if > >>> > > > > > > > >> > > > > > > > > > > > a previous request is delayed > >>> > somewhere. > >>> > > > But > >>> > > > > > > yes, > >>> > > > > > > > in > >>> > > > > > > > >> > this > >>> > > > > > > > >> > > > > case > >>> > > > > > > > >> > > > > > I > >>> > > > > > > > >> > > > > > > > > think > >>> > > > > > > > >> > > > > > > > > > we > >>> > > > > > > > >> > > > > > > > > > > > would fence the client. > >>> > > > > > > > >> > > > > > > > > > > > > >>> > > > > > > > >> > > > > > > > > > > > Not for the overflow case. In > the > >>> > > overflow > >>> > > > > > case, > >>> > > > > > > > the > >>> > > > > > > > >> > > > producer > >>> > > > > > > > >> > > > > > ID > >>> > > > > > > > >> > > > > > > > and > >>> > > > > > > > >> > > > > > > > > > the > >>> > > > > > > > >> > > > > > > > > > > > epoch are different on the > marker > >>> and > >>> > on > >>> > > > the > >>> > > > > > new > >>> > > > > > > > >> > > > transaction. > >>> > > > > > > > >> > > > > > So > >>> > > > > > > > >> > > > > > > we > >>> > > > > > > > >> > > > > > > > > > want > >>> > > > > > > > >> > > > > > > > > > > > the marker to use the max epoch > >>> but > >>> > the > >>> > > > new > >>> > > > > > > > >> > transaction > >>> > > > > > > > >> > > > > should > >>> > > > > > > > >> > > > > > > > start > >>> > > > > > > > >> > > > > > > > > > > with > >>> > > > > > > > >> > > > > > > > > > > > the new ID and epoch 0 in the > >>> > > > transactional > >>> > > > > > > state. > >>> > > > > > > > >> > > > > > > > > > > > > >>> > > > > > > > >> > > > > > > > > > > > In the server downgrade case, we > >>> want > >>> > to > >>> > > > see > >>> > > > > > the > >>> > > > > > > > >> > producer > >>> > > > > > > > >> > > > ID > >>> > > > > > > > >> > > > > as > >>> > > > > > > > >> > > > > > > > that > >>> > > > > > > > >> > > > > > > > > is > >>> > > > > > > > >> > > > > > > > > > > > what the client will have. If we > >>> > > complete > >>> > > > > the > >>> > > > > > > > >> commit, > >>> > > > > > > > >> > and > >>> > > > > > > > >> > > > the > >>> > > > > > > > >> > > > > > > > > > transaction > >>> > > > > > > > >> > > > > > > > > > > > state is reloaded, we need the > new > >>> > > > producer > >>> > > > > ID > >>> > > > > > > in > >>> > > > > > > > >> the > >>> > > > > > > > >> > > state > >>> > > > > > > > >> > > > > so > >>> > > > > > > > >> > > > > > > > there > >>> > > > > > > > >> > > > > > > > > > > isn't > >>> > > > > > > > >> > > > > > > > > > > > an invalid producer ID mapping. > >>> > > > > > > > >> > > > > > > > > > > > The server downgrade cases are > >>> > > considering > >>> > > > > > > > >> > transactional > >>> > > > > > > > >> > > > > > > > correctness > >>> > > > > > > > >> > > > > > > > > > and > >>> > > > > > > > >> > > > > > > > > > > > not regressing from previous > >>> behavior > >>> > -- > >>> > > > and > >>> > > > > > are > >>> > > > > > > > not > >>> > > > > > > > >> > > > > concerned > >>> > > > > > > > >> > > > > > > > about > >>> > > > > > > > >> > > > > > > > > > > > supporting the safety from > fencing > >>> > > retries > >>> > > > > (as > >>> > > > > > > we > >>> > > > > > > > >> have > >>> > > > > > > > >> > > > > > downgraded > >>> > > > > > > > >> > > > > > > > so > >>> > > > > > > > >> > > > > > > > > we > >>> > > > > > > > >> > > > > > > > > > > > don't need to support). Perhaps > >>> this > >>> > is > >>> > > a > >>> > > > > > trade > >>> > > > > > > > off, > >>> > > > > > > > >> > but > >>> > > > > > > > >> > > I > >>> > > > > > > > >> > > > > > think > >>> > > > > > > > >> > > > > > > it > >>> > > > > > > > >> > > > > > > > > is > >>> > > > > > > > >> > > > > > > > > > > the > >>> > > > > > > > >> > > > > > > > > > > > right one. > >>> > > > > > > > >> > > > > > > > > > > > > >>> > > > > > > > >> > > > > > > > > > > > (If the client downgrades, it > will > >>> > have > >>> > > > > > > restarted > >>> > > > > > > > >> and > >>> > > > > > > > >> > it > >>> > > > > > > > >> > > is > >>> > > > > > > > >> > > > > ok > >>> > > > > > > > >> > > > > > > for > >>> > > > > > > > >> > > > > > > > it > >>> > > > > > > > >> > > > > > > > > > to > >>> > > > > > > > >> > > > > > > > > > > > have a new producer ID too). > >>> > > > > > > > >> > > > > > > > > > > > > >>> > > > > > > > >> > > > > > > > > > > > Justine > >>> > > > > > > > >> > > > > > > > > > > > > >>> > > > > > > > >> > > > > > > > > > > > On Fri, Jan 12, 2024 at 11:42 AM > >>> Jun > >>> > Rao > >>> > > > > > > > >> > > > > > > <j...@confluent.io.invalid > >>> > > > > > > > >> > > > > > > > > > >>> > > > > > > > >> > > > > > > > > > > wrote: > >>> > > > > > > > >> > > > > > > > > > > > > >>> > > > > > > > >> > > > > > > > > > > > > Hi, Justine, > >>> > > > > > > > >> > > > > > > > > > > > > > >>> > > > > > > > >> > > > > > > > > > > > > Thanks for the reply. > >>> > > > > > > > >> > > > > > > > > > > > > > >>> > > > > > > > >> > > > > > > > > > > > > 101.4 "If the marker is > written > >>> by > >>> > the > >>> > > > new > >>> > > > > > > > >> client, we > >>> > > > > > > > >> > > can > >>> > > > > > > > >> > > > > as > >>> > > > > > > > >> > > > > > I > >>> > > > > > > > >> > > > > > > > > > > mentioned > >>> > > > > > > > >> > > > > > > > > > > > in > >>> > > > > > > > >> > > > > > > > > > > > > the last email guarantee that > >>> any > >>> > > EndTxn > >>> > > > > > > > requests > >>> > > > > > > > >> > with > >>> > > > > > > > >> > > > the > >>> > > > > > > > >> > > > > > same > >>> > > > > > > > >> > > > > > > > > epoch > >>> > > > > > > > >> > > > > > > > > > > are > >>> > > > > > > > >> > > > > > > > > > > > > from the same producer and the > >>> same > >>> > > > > > > transaction. > >>> > > > > > > > >> Then > >>> > > > > > > > >> > > we > >>> > > > > > > > >> > > > > > don't > >>> > > > > > > > >> > > > > > > > have > >>> > > > > > > > >> > > > > > > > > > to > >>> > > > > > > > >> > > > > > > > > > > > > return a fenced error but can > >>> handle > >>> > > > > > > gracefully > >>> > > > > > > > as > >>> > > > > > > > >> > > > > described > >>> > > > > > > > >> > > > > > in > >>> > > > > > > > >> > > > > > > > the > >>> > > > > > > > >> > > > > > > > > > > KIP." > >>> > > > > > > > >> > > > > > > > > > > > > When a delayed EndTnx request > is > >>> > > > > processed, > >>> > > > > > > the > >>> > > > > > > > >> txn > >>> > > > > > > > >> > > state > >>> > > > > > > > >> > > > > > could > >>> > > > > > > > >> > > > > > > > be > >>> > > > > > > > >> > > > > > > > > > > > ongoing > >>> > > > > > > > >> > > > > > > > > > > > > for the next txn. I guess in > >>> this > >>> > case > >>> > > > we > >>> > > > > > > still > >>> > > > > > > > >> > return > >>> > > > > > > > >> > > > the > >>> > > > > > > > >> > > > > > > fenced > >>> > > > > > > > >> > > > > > > > > > error > >>> > > > > > > > >> > > > > > > > > > > > for > >>> > > > > > > > >> > > > > > > > > > > > > the delayed request? > >>> > > > > > > > >> > > > > > > > > > > > > > >>> > > > > > > > >> > > > > > > > > > > > > 102. Sorry, my question was > >>> > > inaccurate. > >>> > > > > What > >>> > > > > > > you > >>> > > > > > > > >> > > > described > >>> > > > > > > > >> > > > > is > >>> > > > > > > > >> > > > > > > > > > accurate. > >>> > > > > > > > >> > > > > > > > > > > > > "The downgrade compatibility I > >>> > mention > >>> > > > is > >>> > > > > > that > >>> > > > > > > > we > >>> > > > > > > > >> > keep > >>> > > > > > > > >> > > > the > >>> > > > > > > > >> > > > > > same > >>> > > > > > > > >> > > > > > > > > > > producer > >>> > > > > > > > >> > > > > > > > > > > > ID > >>> > > > > > > > >> > > > > > > > > > > > > and epoch in the main > >>> (non-tagged) > >>> > > > fields > >>> > > > > as > >>> > > > > > > we > >>> > > > > > > > >> did > >>> > > > > > > > >> > > > before > >>> > > > > > > > >> > > > > > the > >>> > > > > > > > >> > > > > > > > code > >>> > > > > > > > >> > > > > > > > > > on > >>> > > > > > > > >> > > > > > > > > > > > the > >>> > > > > > > > >> > > > > > > > > > > > > server side." If we want to do > >>> this, > >>> > > it > >>> > > > > > seems > >>> > > > > > > > >> that we > >>> > > > > > > > >> > > > > should > >>> > > > > > > > >> > > > > > > use > >>> > > > > > > > >> > > > > > > > > the > >>> > > > > > > > >> > > > > > > > > > > > > current produce Id and max > >>> epoch in > >>> > > the > >>> > > > > > > existing > >>> > > > > > > > >> > > > producerId > >>> > > > > > > > >> > > > > > and > >>> > > > > > > > >> > > > > > > > > > > > > producerEpoch fields for both > >>> the > >>> > > > prepare > >>> > > > > > and > >>> > > > > > > > the > >>> > > > > > > > >> > > > complete > >>> > > > > > > > >> > > > > > > > marker, > >>> > > > > > > > >> > > > > > > > > > > right? > >>> > > > > > > > >> > > > > > > > > > > > > The downgrade can happen after > >>> the > >>> > > > > complete > >>> > > > > > > > >> marker is > >>> > > > > > > > >> > > > > > written. > >>> > > > > > > > >> > > > > > > > With > >>> > > > > > > > >> > > > > > > > > > > what > >>> > > > > > > > >> > > > > > > > > > > > > you described, the downgraded > >>> > > > coordinator > >>> > > > > > will > >>> > > > > > > > see > >>> > > > > > > > >> > the > >>> > > > > > > > >> > > > new > >>> > > > > > > > >> > > > > > > > produce > >>> > > > > > > > >> > > > > > > > > Id > >>> > > > > > > > >> > > > > > > > > > > > > instead of the old one. > >>> > > > > > > > >> > > > > > > > > > > > > > >>> > > > > > > > >> > > > > > > > > > > > > Jun > >>> > > > > > > > >> > > > > > > > > > > > > > >>> > > > > > > > >> > > > > > > > > > > > > On Fri, Jan 12, 2024 at > 10:44 AM > >>> > > Justine > >>> > > > > > > Olshan > >>> > > > > > > > >> > > > > > > > > > > > > <jols...@confluent.io.invalid > > > >>> > wrote: > >>> > > > > > > > >> > > > > > > > > > > > > > >>> > > > > > > > >> > > > > > > > > > > > > > Hi Jun, > >>> > > > > > > > >> > > > > > > > > > > > > > > >>> > > > > > > > >> > > > > > > > > > > > > > I can update the > description. > >>> > > > > > > > >> > > > > > > > > > > > > > > >>> > > > > > > > >> > > > > > > > > > > > > > I believe your second point > is > >>> > > > mentioned > >>> > > > > > in > >>> > > > > > > > the > >>> > > > > > > > >> > KIP. > >>> > > > > > > > >> > > I > >>> > > > > > > > >> > > > > can > >>> > > > > > > > >> > > > > > > add > >>> > > > > > > > >> > > > > > > > > more > >>> > > > > > > > >> > > > > > > > > > > > text > >>> > > > > > > > >> > > > > > > > > > > > > on > >>> > > > > > > > >> > > > > > > > > > > > > > this if it is helpful. > >>> > > > > > > > >> > > > > > > > > > > > > > > The delayed message case > can > >>> > also > >>> > > > > > violate > >>> > > > > > > > EOS > >>> > > > > > > > >> if > >>> > > > > > > > >> > > the > >>> > > > > > > > >> > > > > > > delayed > >>> > > > > > > > >> > > > > > > > > > > message > >>> > > > > > > > >> > > > > > > > > > > > > > comes in after the next > >>> > > > > addPartitionsToTxn > >>> > > > > > > > >> request > >>> > > > > > > > >> > > > comes > >>> > > > > > > > >> > > > > > in. > >>> > > > > > > > >> > > > > > > > > > > > Effectively > >>> > > > > > > > >> > > > > > > > > > > > > we > >>> > > > > > > > >> > > > > > > > > > > > > > may see a message from a > >>> previous > >>> > > > > > (aborted) > >>> > > > > > > > >> > > transaction > >>> > > > > > > > >> > > > > > > become > >>> > > > > > > > >> > > > > > > > > part > >>> > > > > > > > >> > > > > > > > > > > of > >>> > > > > > > > >> > > > > > > > > > > > > the > >>> > > > > > > > >> > > > > > > > > > > > > > next transaction. > >>> > > > > > > > >> > > > > > > > > > > > > > > >>> > > > > > > > >> > > > > > > > > > > > > > If the marker is written by > >>> the > >>> > new > >>> > > > > > client, > >>> > > > > > > we > >>> > > > > > > > >> can > >>> > > > > > > > >> > > as I > >>> > > > > > > > >> > > > > > > > mentioned > >>> > > > > > > > >> > > > > > > > > > in > >>> > > > > > > > >> > > > > > > > > > > > the > >>> > > > > > > > >> > > > > > > > > > > > > > last email guarantee that > any > >>> > EndTxn > >>> > > > > > > requests > >>> > > > > > > > >> with > >>> > > > > > > > >> > > the > >>> > > > > > > > >> > > > > same > >>> > > > > > > > >> > > > > > > > epoch > >>> > > > > > > > >> > > > > > > > > > are > >>> > > > > > > > >> > > > > > > > > > > > > from > >>> > > > > > > > >> > > > > > > > > > > > > > the same producer and the > same > >>> > > > > > transaction. > >>> > > > > > > > >> Then we > >>> > > > > > > > >> > > > don't > >>> > > > > > > > >> > > > > > > have > >>> > > > > > > > >> > > > > > > > to > >>> > > > > > > > >> > > > > > > > > > > > return > >>> > > > > > > > >> > > > > > > > > > > > > a > >>> > > > > > > > >> > > > > > > > > > > > > > fenced error but can handle > >>> > > gracefully > >>> > > > > as > >>> > > > > > > > >> described > >>> > > > > > > > >> > > in > >>> > > > > > > > >> > > > > the > >>> > > > > > > > >> > > > > > > KIP. > >>> > > > > > > > >> > > > > > > > > > > > > > I don't think a boolean is > >>> useful > >>> > > > since > >>> > > > > it > >>> > > > > > > is > >>> > > > > > > > >> > > directly > >>> > > > > > > > >> > > > > > > encoded > >>> > > > > > > > >> > > > > > > > by > >>> > > > > > > > >> > > > > > > > > > the > >>> > > > > > > > >> > > > > > > > > > > > > > existence or lack of the > >>> tagged > >>> > > field > >>> > > > > > being > >>> > > > > > > > >> > written. > >>> > > > > > > > >> > > > > > > > > > > > > > In the prepare marker we > will > >>> have > >>> > > the > >>> > > > > > same > >>> > > > > > > > >> > producer > >>> > > > > > > > >> > > ID > >>> > > > > > > > >> > > > > in > >>> > > > > > > > >> > > > > > > the > >>> > > > > > > > >> > > > > > > > > > > > non-tagged > >>> > > > > > > > >> > > > > > > > > > > > > > field. In the Complete state > >>> we > >>> > may > >>> > > > not. > >>> > > > > > > > >> > > > > > > > > > > > > > I'm not sure why the ongoing > >>> state > >>> > > > > matters > >>> > > > > > > for > >>> > > > > > > > >> this > >>> > > > > > > > >> > > > KIP. > >>> > > > > > > > >> > > > > It > >>> > > > > > > > >> > > > > > > > does > >>> > > > > > > > >> > > > > > > > > > > matter > >>> > > > > > > > >> > > > > > > > > > > > > for > >>> > > > > > > > >> > > > > > > > > > > > > > KIP-939. > >>> > > > > > > > >> > > > > > > > > > > > > > > >>> > > > > > > > >> > > > > > > > > > > > > > I'm not sure what you are > >>> > referring > >>> > > to > >>> > > > > > about > >>> > > > > > > > >> > writing > >>> > > > > > > > >> > > > the > >>> > > > > > > > >> > > > > > > > previous > >>> > > > > > > > >> > > > > > > > > > > > > producer > >>> > > > > > > > >> > > > > > > > > > > > > > ID in the prepare marker. > >>> This is > >>> > > not > >>> > > > in > >>> > > > > > the > >>> > > > > > > > >> KIP. > >>> > > > > > > > >> > > > > > > > > > > > > > In the overflow case, we > >>> write the > >>> > > > > > > > >> nextProducerId > >>> > > > > > > > >> > in > >>> > > > > > > > >> > > > the > >>> > > > > > > > >> > > > > > > > prepare > >>> > > > > > > > >> > > > > > > > > > > state. > >>> > > > > > > > >> > > > > > > > > > > > > > This is so we know what we > >>> > assigned > >>> > > > when > >>> > > > > > we > >>> > > > > > > > >> reload > >>> > > > > > > > >> > > the > >>> > > > > > > > >> > > > > > > > > transaction > >>> > > > > > > > >> > > > > > > > > > > log. > >>> > > > > > > > >> > > > > > > > > > > > > > Once we complete, we > >>> transition > >>> > this > >>> > > > ID > >>> > > > > to > >>> > > > > > > the > >>> > > > > > > > >> main > >>> > > > > > > > >> > > > > > > (non-tagged > >>> > > > > > > > >> > > > > > > > > > > field) > >>> > > > > > > > >> > > > > > > > > > > > > and > >>> > > > > > > > >> > > > > > > > > > > > > > have the previous producer > ID > >>> > field > >>> > > > > filled > >>> > > > > > > in. > >>> > > > > > > > >> This > >>> > > > > > > > >> > > is > >>> > > > > > > > >> > > > so > >>> > > > > > > > >> > > > > > we > >>> > > > > > > > >> > > > > > > > can > >>> > > > > > > > >> > > > > > > > > > > > identify > >>> > > > > > > > >> > > > > > > > > > > > > > in a retry case the > operation > >>> > > > completed > >>> > > > > > > > >> > successfully > >>> > > > > > > > >> > > > and > >>> > > > > > > > >> > > > > we > >>> > > > > > > > >> > > > > > > > don't > >>> > > > > > > > >> > > > > > > > > > > fence > >>> > > > > > > > >> > > > > > > > > > > > > our > >>> > > > > > > > >> > > > > > > > > > > > > > producer. The downgrade > >>> > > compatibility > >>> > > > I > >>> > > > > > > > mention > >>> > > > > > > > >> is > >>> > > > > > > > >> > > that > >>> > > > > > > > >> > > > > we > >>> > > > > > > > >> > > > > > > keep > >>> > > > > > > > >> > > > > > > > > the > >>> > > > > > > > >> > > > > > > > > > > > same > >>> > > > > > > > >> > > > > > > > > > > > > > producer ID and epoch in the > >>> main > >>> > > > > > > (non-tagged) > >>> > > > > > > > >> > fields > >>> > > > > > > > >> > > > as > >>> > > > > > > > >> > > > > we > >>> > > > > > > > >> > > > > > > did > >>> > > > > > > > >> > > > > > > > > > > before > >>> > > > > > > > >> > > > > > > > > > > > > the > >>> > > > > > > > >> > > > > > > > > > > > > > code on the server side. If > >>> the > >>> > > server > >>> > > > > > > > >> downgrades, > >>> > > > > > > > >> > we > >>> > > > > > > > >> > > > are > >>> > > > > > > > >> > > > > > > still > >>> > > > > > > > >> > > > > > > > > > > > > compatible. > >>> > > > > > > > >> > > > > > > > > > > > > > This addresses both the > >>> prepare > >>> > and > >>> > > > > > complete > >>> > > > > > > > >> state > >>> > > > > > > > >> > > > > > > downgrades. > >>> > > > > > > > >> > > > > > > > > > > > > > > >>> > > > > > > > >> > > > > > > > > > > > > > Justine > >>> > > > > > > > >> > > > > > > > > > > > > > > >>> > > > > > > > >> > > > > > > > > > > > > > On Fri, Jan 12, 2024 at > >>> 10:21 AM > >>> > Jun > >>> > > > Rao > >>> > > > > > > > >> > > > > > > > > <j...@confluent.io.invalid > >>> > > > > > > > >> > > > > > > > > > > > >>> > > > > > > > >> > > > > > > > > > > > > wrote: > >>> > > > > > > > >> > > > > > > > > > > > > > > >>> > > > > > > > >> > > > > > > > > > > > > > > Hi, Justine, > >>> > > > > > > > >> > > > > > > > > > > > > > > > >>> > > > > > > > >> > > > > > > > > > > > > > > Thanks for the reply. > Sorry > >>> for > >>> > > the > >>> > > > > > > delay. I > >>> > > > > > > > >> > have a > >>> > > > > > > > >> > > > few > >>> > > > > > > > >> > > > > > > more > >>> > > > > > > > >> > > > > > > > > > > > comments. > >>> > > > > > > > >> > > > > > > > > > > > > > > > >>> > > > > > > > >> > > > > > > > > > > > > > > 110. I think the > motivation > >>> > > section > >>> > > > > > could > >>> > > > > > > be > >>> > > > > > > > >> > > > improved. > >>> > > > > > > > >> > > > > > One > >>> > > > > > > > >> > > > > > > of > >>> > > > > > > > >> > > > > > > > > the > >>> > > > > > > > >> > > > > > > > > > > > > > > motivations listed by the > >>> KIP is > >>> > > > "This > >>> > > > > > can > >>> > > > > > > > >> happen > >>> > > > > > > > >> > > > when > >>> > > > > > > > >> > > > > a > >>> > > > > > > > >> > > > > > > > > message > >>> > > > > > > > >> > > > > > > > > > > gets > >>> > > > > > > > >> > > > > > > > > > > > > > stuck > >>> > > > > > > > >> > > > > > > > > > > > > > > or delayed due to > networking > >>> > > issues > >>> > > > > or a > >>> > > > > > > > >> network > >>> > > > > > > > >> > > > > > partition, > >>> > > > > > > > >> > > > > > > > the > >>> > > > > > > > >> > > > > > > > > > > > > > transaction > >>> > > > > > > > >> > > > > > > > > > > > > > > aborts, and then the > delayed > >>> > > message > >>> > > > > > > finally > >>> > > > > > > > >> > comes > >>> > > > > > > > >> > > > > in.". > >>> > > > > > > > >> > > > > > > This > >>> > > > > > > > >> > > > > > > > > > seems > >>> > > > > > > > >> > > > > > > > > > > > not > >>> > > > > > > > >> > > > > > > > > > > > > > > very accurate. Without > >>> KIP-890, > >>> > > > > > currently, > >>> > > > > > > > if > >>> > > > > > > > >> the > >>> > > > > > > > >> > > > > > > coordinator > >>> > > > > > > > >> > > > > > > > > > times > >>> > > > > > > > >> > > > > > > > > > > > out > >>> > > > > > > > >> > > > > > > > > > > > > > and > >>> > > > > > > > >> > > > > > > > > > > > > > > aborts an ongoing > >>> transaction, > >>> > it > >>> > > > > > already > >>> > > > > > > > >> bumps > >>> > > > > > > > >> > up > >>> > > > > > > > >> > > > the > >>> > > > > > > > >> > > > > > > epoch > >>> > > > > > > > >> > > > > > > > in > >>> > > > > > > > >> > > > > > > > > > the > >>> > > > > > > > >> > > > > > > > > > > > > > marker, > >>> > > > > > > > >> > > > > > > > > > > > > > > which prevents the delayed > >>> > produce > >>> > > > > > message > >>> > > > > > > > >> from > >>> > > > > > > > >> > > being > >>> > > > > > > > >> > > > > > added > >>> > > > > > > > >> > > > > > > > to > >>> > > > > > > > >> > > > > > > > > > the > >>> > > > > > > > >> > > > > > > > > > > > user > >>> > > > > > > > >> > > > > > > > > > > > > > > partition. What can cause > a > >>> > > hanging > >>> > > > > > > > >> transaction > >>> > > > > > > > >> > is > >>> > > > > > > > >> > > > that > >>> > > > > > > > >> > > > > > the > >>> > > > > > > > >> > > > > > > > > > > producer > >>> > > > > > > > >> > > > > > > > > > > > > > > completes (either aborts > or > >>> > > > commits) a > >>> > > > > > > > >> > transaction > >>> > > > > > > > >> > > > > before > >>> > > > > > > > >> > > > > > > > > > > receiving a > >>> > > > > > > > >> > > > > > > > > > > > > > > successful ack on messages > >>> > > published > >>> > > > > in > >>> > > > > > > the > >>> > > > > > > > >> same > >>> > > > > > > > >> > > txn. > >>> > > > > > > > >> > > > > In > >>> > > > > > > > >> > > > > > > this > >>> > > > > > > > >> > > > > > > > > > case, > >>> > > > > > > > >> > > > > > > > > > > > > it's > >>> > > > > > > > >> > > > > > > > > > > > > > > possible for the delayed > >>> message > >>> > > to > >>> > > > be > >>> > > > > > > > >> appended > >>> > > > > > > > >> > to > >>> > > > > > > > >> > > > the > >>> > > > > > > > >> > > > > > > > > partition > >>> > > > > > > > >> > > > > > > > > > > > after > >>> > > > > > > > >> > > > > > > > > > > > > > the > >>> > > > > > > > >> > > > > > > > > > > > > > > marker, causing a > >>> transaction to > >>> > > > hang. > >>> > > > > > > > >> > > > > > > > > > > > > > > > >>> > > > > > > > >> > > > > > > > > > > > > > > A similar issue (not > >>> mentioned > >>> > in > >>> > > > the > >>> > > > > > > > >> motivation) > >>> > > > > > > > >> > > > could > >>> > > > > > > > >> > > > > > > > happen > >>> > > > > > > > >> > > > > > > > > on > >>> > > > > > > > >> > > > > > > > > > > the > >>> > > > > > > > >> > > > > > > > > > > > > > > marker in the > coordinator's > >>> log. > >>> > > For > >>> > > > > > > > example, > >>> > > > > > > > >> > it's > >>> > > > > > > > >> > > > > > possible > >>> > > > > > > > >> > > > > > > > for > >>> > > > > > > > >> > > > > > > > > > an > >>> > > > > > > > >> > > > > > > > > > > > > > > EndTxnRequest to be > delayed > >>> on > >>> > the > >>> > > > > > > > >> coordinator. > >>> > > > > > > > >> > By > >>> > > > > > > > >> > > > the > >>> > > > > > > > >> > > > > > time > >>> > > > > > > > >> > > > > > > > the > >>> > > > > > > > >> > > > > > > > > > > > delayed > >>> > > > > > > > >> > > > > > > > > > > > > > > EndTxnRequest is > processed, > >>> it's > >>> > > > > > possible > >>> > > > > > > > that > >>> > > > > > > > >> > the > >>> > > > > > > > >> > > > > > previous > >>> > > > > > > > >> > > > > > > > txn > >>> > > > > > > > >> > > > > > > > > > has > >>> > > > > > > > >> > > > > > > > > > > > > > already > >>> > > > > > > > >> > > > > > > > > > > > > > > completed and a new txn > has > >>> > > started. > >>> > > > > > > > >> Currently, > >>> > > > > > > > >> > > since > >>> > > > > > > > >> > > > > the > >>> > > > > > > > >> > > > > > > > epoch > >>> > > > > > > > >> > > > > > > > > > is > >>> > > > > > > > >> > > > > > > > > > > > not > >>> > > > > > > > >> > > > > > > > > > > > > > > bumped on every txn, the > >>> delayed > >>> > > > > > > > EndTxnRequest > >>> > > > > > > > >> > will > >>> > > > > > > > >> > > > add > >>> > > > > > > > >> > > > > > an > >>> > > > > > > > >> > > > > > > > > > > unexpected > >>> > > > > > > > >> > > > > > > > > > > > > > > prepare marker (and > >>> eventually a > >>> > > > > > complete > >>> > > > > > > > >> marker) > >>> > > > > > > > >> > > to > >>> > > > > > > > >> > > > > the > >>> > > > > > > > >> > > > > > > > > ongoing > >>> > > > > > > > >> > > > > > > > > > > txn. > >>> > > > > > > > >> > > > > > > > > > > > > > This > >>> > > > > > > > >> > > > > > > > > > > > > > > won't cause the > transaction > >>> to > >>> > > hang, > >>> > > > > but > >>> > > > > > > it > >>> > > > > > > > >> will > >>> > > > > > > > >> > > > break > >>> > > > > > > > >> > > > > > the > >>> > > > > > > > >> > > > > > > > EoS > >>> > > > > > > > >> > > > > > > > > > > > > semantic. > >>> > > > > > > > >> > > > > > > > > > > > > > > The proposal in this KIP > >>> will > >>> > > > address > >>> > > > > > this > >>> > > > > > > > >> issue > >>> > > > > > > > >> > > too. > >>> > > > > > > > >> > > > > > > > > > > > > > > > >>> > > > > > > > >> > > > > > > > > > > > > > > 101. "However, I was > >>> writing it > >>> > so > >>> > > > > that > >>> > > > > > we > >>> > > > > > > > can > >>> > > > > > > > >> > > > > > distinguish > >>> > > > > > > > >> > > > > > > > > > between > >>> > > > > > > > >> > > > > > > > > > > > > > > old clients where we don't > >>> have > >>> > > the > >>> > > > > > > ability > >>> > > > > > > > do > >>> > > > > > > > >> > this > >>> > > > > > > > >> > > > > > > operation > >>> > > > > > > > >> > > > > > > > > and > >>> > > > > > > > >> > > > > > > > > > > new > >>> > > > > > > > >> > > > > > > > > > > > > > > clients that can. (Old > >>> clients > >>> > > don't > >>> > > > > > bump > >>> > > > > > > > the > >>> > > > > > > > >> > epoch > >>> > > > > > > > >> > > > on > >>> > > > > > > > >> > > > > > > > commit, > >>> > > > > > > > >> > > > > > > > > so > >>> > > > > > > > >> > > > > > > > > > > we > >>> > > > > > > > >> > > > > > > > > > > > > > can't > >>> > > > > > > > >> > > > > > > > > > > > > > > say for sure the write > >>> belongs > >>> > to > >>> > > > the > >>> > > > > > > given > >>> > > > > > > > >> > > > > > transaction)." > >>> > > > > > > > >> > > > > > > > > > > > > > > 101.1 I am wondering why > we > >>> need > >>> > > to > >>> > > > > > > > >> distinguish > >>> > > > > > > > >> > > > whether > >>> > > > > > > > >> > > > > > the > >>> > > > > > > > >> > > > > > > > > > marker > >>> > > > > > > > >> > > > > > > > > > > is > >>> > > > > > > > >> > > > > > > > > > > > > > > written by the old and the > >>> new > >>> > > > client. > >>> > > > > > > Could > >>> > > > > > > > >> you > >>> > > > > > > > >> > > > > describe > >>> > > > > > > > >> > > > > > > > what > >>> > > > > > > > >> > > > > > > > > we > >>> > > > > > > > >> > > > > > > > > > > do > >>> > > > > > > > >> > > > > > > > > > > > > > > differently if we know the > >>> > marker > >>> > > is > >>> > > > > > > written > >>> > > > > > > > >> by > >>> > > > > > > > >> > the > >>> > > > > > > > >> > > > new > >>> > > > > > > > >> > > > > > > > client? > >>> > > > > > > > >> > > > > > > > > > > > > > > 101.2 If we do need a way > to > >>> > > > > distinguish > >>> > > > > > > > >> whether > >>> > > > > > > > >> > > the > >>> > > > > > > > >> > > > > > marker > >>> > > > > > > > >> > > > > > > > is > >>> > > > > > > > >> > > > > > > > > > > > written > >>> > > > > > > > >> > > > > > > > > > > > > by > >>> > > > > > > > >> > > > > > > > > > > > > > > the old and the new > client. > >>> > Would > >>> > > it > >>> > > > > be > >>> > > > > > > > >> simpler > >>> > > > > > > > >> > to > >>> > > > > > > > >> > > > just > >>> > > > > > > > >> > > > > > > > > > introduce a > >>> > > > > > > > >> > > > > > > > > > > > > > boolean > >>> > > > > > > > >> > > > > > > > > > > > > > > field instead of > indirectly > >>> > > through > >>> > > > > the > >>> > > > > > > > >> previous > >>> > > > > > > > >> > > > > produce > >>> > > > > > > > >> > > > > > ID > >>> > > > > > > > >> > > > > > > > > > field? > >>> > > > > > > > >> > > > > > > > > > > > > > > 101.3 It's not clear to me > >>> why > >>> > we > >>> > > > only > >>> > > > > > add > >>> > > > > > > > the > >>> > > > > > > > >> > > > previous > >>> > > > > > > > >> > > > > > > > produce > >>> > > > > > > > >> > > > > > > > > > ID > >>> > > > > > > > >> > > > > > > > > > > > > field > >>> > > > > > > > >> > > > > > > > > > > > > > in > >>> > > > > > > > >> > > > > > > > > > > > > > > the complete marker, but > >>> not in > >>> > > the > >>> > > > > > > prepare > >>> > > > > > > > >> > marker. > >>> > > > > > > > >> > > > If > >>> > > > > > > > >> > > > > we > >>> > > > > > > > >> > > > > > > > want > >>> > > > > > > > >> > > > > > > > > to > >>> > > > > > > > >> > > > > > > > > > > > know > >>> > > > > > > > >> > > > > > > > > > > > > > > whether a marker is > written > >>> by > >>> > the > >>> > > > new > >>> > > > > > > > client > >>> > > > > > > > >> or > >>> > > > > > > > >> > > not, > >>> > > > > > > > >> > > > > it > >>> > > > > > > > >> > > > > > > > seems > >>> > > > > > > > >> > > > > > > > > > that > >>> > > > > > > > >> > > > > > > > > > > > we > >>> > > > > > > > >> > > > > > > > > > > > > > want > >>> > > > > > > > >> > > > > > > > > > > > > > > to do this consistently > for > >>> all > >>> > > > > markers. > >>> > > > > > > > >> > > > > > > > > > > > > > > 101.4 What about the > >>> > > > > TransactionLogValue > >>> > > > > > > > >> record > >>> > > > > > > > >> > > > > > > representing > >>> > > > > > > > >> > > > > > > > > the > >>> > > > > > > > >> > > > > > > > > > > > > ongoing > >>> > > > > > > > >> > > > > > > > > > > > > > > state? Should we also > >>> > distinguish > >>> > > > > > whether > >>> > > > > > > > it's > >>> > > > > > > > >> > > > written > >>> > > > > > > > >> > > > > by > >>> > > > > > > > >> > > > > > > the > >>> > > > > > > > >> > > > > > > > > old > >>> > > > > > > > >> > > > > > > > > > > or > >>> > > > > > > > >> > > > > > > > > > > > > the > >>> > > > > > > > >> > > > > > > > > > > > > > > new client? > >>> > > > > > > > >> > > > > > > > > > > > > > > > >>> > > > > > > > >> > > > > > > > > > > > > > > 102. In the overflow case, > >>> it's > >>> > > > still > >>> > > > > > not > >>> > > > > > > > >> clear > >>> > > > > > > > >> > to > >>> > > > > > > > >> > > me > >>> > > > > > > > >> > > > > why > >>> > > > > > > > >> > > > > > > we > >>> > > > > > > > >> > > > > > > > > > write > >>> > > > > > > > >> > > > > > > > > > > > the > >>> > > > > > > > >> > > > > > > > > > > > > > > previous produce Id in the > >>> > prepare > >>> > > > > > marker > >>> > > > > > > > >> while > >>> > > > > > > > >> > > > writing > >>> > > > > > > > >> > > > > > the > >>> > > > > > > > >> > > > > > > > > next > >>> > > > > > > > >> > > > > > > > > > > > > produce > >>> > > > > > > > >> > > > > > > > > > > > > > Id > >>> > > > > > > > >> > > > > > > > > > > > > > > in the complete marker. > You > >>> > > > mentioned > >>> > > > > > that > >>> > > > > > > > >> it's > >>> > > > > > > > >> > for > >>> > > > > > > > >> > > > > > > > > downgrading. > >>> > > > > > > > >> > > > > > > > > > > > > However, > >>> > > > > > > > >> > > > > > > > > > > > > > > we could downgrade with > >>> either > >>> > the > >>> > > > > > prepare > >>> > > > > > > > >> marker > >>> > > > > > > > >> > > or > >>> > > > > > > > >> > > > > the > >>> > > > > > > > >> > > > > > > > > complete > >>> > > > > > > > >> > > > > > > > > > > > > marker. > >>> > > > > > > > >> > > > > > > > > > > > > > > In either case, the > >>> downgraded > >>> > > > > > coordinator > >>> > > > > > > > >> should > >>> > > > > > > > >> > > see > >>> > > > > > > > >> > > > > the > >>> > > > > > > > >> > > > > > > > same > >>> > > > > > > > >> > > > > > > > > > > > produce > >>> > > > > > > > >> > > > > > > > > > > > > id > >>> > > > > > > > >> > > > > > > > > > > > > > > (probably the previous > >>> produce > >>> > > Id), > >>> > > > > > right? > >>> > > > > > > > >> > > > > > > > > > > > > > > > >>> > > > > > > > >> > > > > > > > > > > > > > > Jun > >>> > > > > > > > >> > > > > > > > > > > > > > > > >>> > > > > > > > >> > > > > > > > > > > > > > > On Wed, Dec 20, 2023 at > >>> 6:00 PM > >>> > > > > Justine > >>> > > > > > > > Olshan > >>> > > > > > > > >> > > > > > > > > > > > > > > > >>> <jols...@confluent.io.invalid> > >>> > > > > > > > >> > > > > > > > > > > > > > > wrote: > >>> > > > > > > > >> > > > > > > > > > > > > > > > >>> > > > > > > > >> > > > > > > > > > > > > > > > Hey Jun, > >>> > > > > > > > >> > > > > > > > > > > > > > > > > >>> > > > > > > > >> > > > > > > > > > > > > > > > Thanks for taking a look > >>> at > >>> > the > >>> > > > KIP > >>> > > > > > > again. > >>> > > > > > > > >> > > > > > > > > > > > > > > > > >>> > > > > > > > >> > > > > > > > > > > > > > > > 100. For the epoch > >>> overflow > >>> > > case, > >>> > > > > only > >>> > > > > > > the > >>> > > > > > > > >> > marker > >>> > > > > > > > >> > > > > will > >>> > > > > > > > >> > > > > > > have > >>> > > > > > > > >> > > > > > > > > max > >>> > > > > > > > >> > > > > > > > > > > > > epoch. > >>> > > > > > > > >> > > > > > > > > > > > > > > This > >>> > > > > > > > >> > > > > > > > > > > > > > > > keeps the behavior of > the > >>> rest > >>> > > of > >>> > > > > the > >>> > > > > > > > >> markers > >>> > > > > > > > >> > > where > >>> > > > > > > > >> > > > > the > >>> > > > > > > > >> > > > > > > > last > >>> > > > > > > > >> > > > > > > > > > > marker > >>> > > > > > > > >> > > > > > > > > > > > > is > >>> > > > > > > > >> > > > > > > > > > > > > > > the > >>> > > > > > > > >> > > > > > > > > > > > > > > > epoch of the transaction > >>> > > records + > >>> > > > > 1. > >>> > > > > > > > >> > > > > > > > > > > > > > > > > >>> > > > > > > > >> > > > > > > > > > > > > > > > 101. You are correct > that > >>> we > >>> > > don't > >>> > > > > > need > >>> > > > > > > to > >>> > > > > > > > >> > write > >>> > > > > > > > >> > > > the > >>> > > > > > > > >> > > > > > > > producer > >>> > > > > > > > >> > > > > > > > > > ID > >>> > > > > > > > >> > > > > > > > > > > > > since > >>> > > > > > > > >> > > > > > > > > > > > > > it > >>> > > > > > > > >> > > > > > > > > > > > > > > > is the same. However, I > >>> was > >>> > > > writing > >>> > > > > it > >>> > > > > > > so > >>> > > > > > > > >> that > >>> > > > > > > > >> > we > >>> > > > > > > > >> > > > can > >>> > > > > > > > >> > > > > > > > > > distinguish > >>> > > > > > > > >> > > > > > > > > > > > > > between > >>> > > > > > > > >> > > > > > > > > > > > > > > > old clients where we > don't > >>> > have > >>> > > > the > >>> > > > > > > > ability > >>> > > > > > > > >> do > >>> > > > > > > > >> > > this > >>> > > > > > > > >> > > > > > > > operation > >>> > > > > > > > >> > > > > > > > > > and > >>> > > > > > > > >> > > > > > > > > > > > new > >>> > > > > > > > >> > > > > > > > > > > > > > > > clients that can. (Old > >>> clients > >>> > > > don't > >>> > > > > > > bump > >>> > > > > > > > >> the > >>> > > > > > > > >> > > epoch > >>> > > > > > > > >> > > > > on > >>> > > > > > > > >> > > > > > > > > commit, > >>> > > > > > > > >> > > > > > > > > > so > >>> > > > > > > > >> > > > > > > > > > > > we > >>> > > > > > > > >> > > > > > > > > > > > > > > can't > >>> > > > > > > > >> > > > > > > > > > > > > > > > say for sure the write > >>> belongs > >>> > > to > >>> > > > > the > >>> > > > > > > > given > >>> > > > > > > > >> > > > > > transaction). > >>> > > > > > > > >> > > > > > > > If > >>> > > > > > > > >> > > > > > > > > we > >>> > > > > > > > >> > > > > > > > > > > > > receive > >>> > > > > > > > >> > > > > > > > > > > > > > > an > >>> > > > > > > > >> > > > > > > > > > > > > > > > EndTxn request from a > new > >>> > > client, > >>> > > > we > >>> > > > > > > will > >>> > > > > > > > >> fill > >>> > > > > > > > >> > > this > >>> > > > > > > > >> > > > > > > field. > >>> > > > > > > > >> > > > > > > > We > >>> > > > > > > > >> > > > > > > > > > can > >>> > > > > > > > >> > > > > > > > > > > > > > > guarantee > >>> > > > > > > > >> > > > > > > > > > > > > > > > that any EndTxn requests > >>> with > >>> > > the > >>> > > > > same > >>> > > > > > > > epoch > >>> > > > > > > > >> > are > >>> > > > > > > > >> > > > from > >>> > > > > > > > >> > > > > > the > >>> > > > > > > > >> > > > > > > > > same > >>> > > > > > > > >> > > > > > > > > > > > > producer > >>> > > > > > > > >> > > > > > > > > > > > > > > and > >>> > > > > > > > >> > > > > > > > > > > > > > > > the same transaction. > >>> > > > > > > > >> > > > > > > > > > > > > > > > > >>> > > > > > > > >> > > > > > > > > > > > > > > > 102. In prepare phase, > we > >>> have > >>> > > the > >>> > > > > > same > >>> > > > > > > > >> > producer > >>> > > > > > > > >> > > ID > >>> > > > > > > > >> > > > > and > >>> > > > > > > > >> > > > > > > > epoch > >>> > > > > > > > >> > > > > > > > > > we > >>> > > > > > > > >> > > > > > > > > > > > > always > >>> > > > > > > > >> > > > > > > > > > > > > > > > had. It is the producer > >>> ID and > >>> > > > epoch > >>> > > > > > > that > >>> > > > > > > > >> are > >>> > > > > > > > >> > on > >>> > > > > > > > >> > > > the > >>> > > > > > > > >> > > > > > > > marker. > >>> > > > > > > > >> > > > > > > > > In > >>> > > > > > > > >> > > > > > > > > > > > > commit > >>> > > > > > > > >> > > > > > > > > > > > > > > > phase, we stay the same > >>> unless > >>> > > it > >>> > > > is > >>> > > > > > the > >>> > > > > > > > >> > overflow > >>> > > > > > > > >> > > > > case. > >>> > > > > > > > >> > > > > > > In > >>> > > > > > > > >> > > > > > > > > that > >>> > > > > > > > >> > > > > > > > > > > > case, > >>> > > > > > > > >> > > > > > > > > > > > > > we > >>> > > > > > > > >> > > > > > > > > > > > > > > > set the producer ID to > >>> the new > >>> > > one > >>> > > > > we > >>> > > > > > > > >> generated > >>> > > > > > > > >> > > and > >>> > > > > > > > >> > > > > > epoch > >>> > > > > > > > >> > > > > > > > to > >>> > > > > > > > >> > > > > > > > > 0 > >>> > > > > > > > >> > > > > > > > > > > > after > >>> > > > > > > > >> > > > > > > > > > > > > > > > complete. This is for > >>> > downgrade > >>> > > > > > > > >> compatibility. > >>> > > > > > > > >> > > The > >>> > > > > > > > >> > > > > > tagged > >>> > > > > > > > >> > > > > > > > > > fields > >>> > > > > > > > >> > > > > > > > > > > > are > >>> > > > > > > > >> > > > > > > > > > > > > > just > >>> > > > > > > > >> > > > > > > > > > > > > > > > safety guards for > retries > >>> and > >>> > > > > > failovers. > >>> > > > > > > > >> > > > > > > > > > > > > > > > > >>> > > > > > > > >> > > > > > > > > > > > > > > > In prepare phase for > epoch > >>> > > > overflow > >>> > > > > > case > >>> > > > > > > > >> only > >>> > > > > > > > >> > we > >>> > > > > > > > >> > > > > store > >>> > > > > > > > >> > > > > > > the > >>> > > > > > > > >> > > > > > > > > next > >>> > > > > > > > >> > > > > > > > > > > > > > producer > >>> > > > > > > > >> > > > > > > > > > > > > > > > ID. This is for the case > >>> where > >>> > > we > >>> > > > > > reload > >>> > > > > > > > the > >>> > > > > > > > >> > > > > > transaction > >>> > > > > > > > >> > > > > > > > > > > > coordinator > >>> > > > > > > > >> > > > > > > > > > > > > in > >>> > > > > > > > >> > > > > > > > > > > > > > > > prepare state. Once the > >>> > > > transaction > >>> > > > > is > >>> > > > > > > > >> > committed, > >>> > > > > > > > >> > > > we > >>> > > > > > > > >> > > > > > can > >>> > > > > > > > >> > > > > > > > use > >>> > > > > > > > >> > > > > > > > > > the > >>> > > > > > > > >> > > > > > > > > > > > > > producer > >>> > > > > > > > >> > > > > > > > > > > > > > > > ID the client already is > >>> > using. > >>> > > > > > > > >> > > > > > > > > > > > > > > > > >>> > > > > > > > >> > > > > > > > > > > > > > > > In commit phase, we > store > >>> the > >>> > > > > previous > >>> > > > > > > > >> producer > >>> > > > > > > > >> > > ID > >>> > > > > > > > >> > > > in > >>> > > > > > > > >> > > > > > > case > >>> > > > > > > > >> > > > > > > > of > >>> > > > > > > > >> > > > > > > > > > > > > retries. > >>> > > > > > > > >> > > > > > > > > > > > > > > > > >>> > > > > > > > >> > > > > > > > > > > > > > > > I think it is easier to > >>> think > >>> > of > >>> > > > it > >>> > > > > as > >>> > > > > > > > just > >>> > > > > > > > >> how > >>> > > > > > > > >> > > we > >>> > > > > > > > >> > > > > were > >>> > > > > > > > >> > > > > > > > > storing > >>> > > > > > > > >> > > > > > > > > > > > > > producer > >>> > > > > > > > >> > > > > > > > > > > > > > > ID > >>> > > > > > > > >> > > > > > > > > > > > > > > > and epoch before, with > >>> some > >>> > > extra > >>> > > > > > > > bookeeping > >>> > > > > > > > >> > and > >>> > > > > > > > >> > > > edge > >>> > > > > > > > >> > > > > > > case > >>> > > > > > > > >> > > > > > > > > > > handling > >>> > > > > > > > >> > > > > > > > > > > > > in > >>> > > > > > > > >> > > > > > > > > > > > > > > the > >>> > > > > > > > >> > > > > > > > > > > > > > > > tagged fields. We have > to > >>> do > >>> > it > >>> > > > this > >>> > > > > > way > >>> > > > > > > > for > >>> > > > > > > > >> > > > > > > compatibility > >>> > > > > > > > >> > > > > > > > > with > >>> > > > > > > > >> > > > > > > > > > > > > > > downgrades. > >>> > > > > > > > >> > > > > > > > > > > > > > > > > >>> > > > > > > > >> > > > > > > > > > > > > > > > 103. Next producer ID is > >>> for > >>> > > > prepare > >>> > > > > > > > status > >>> > > > > > > > >> and > >>> > > > > > > > >> > > > > > previous > >>> > > > > > > > >> > > > > > > > > > producer > >>> > > > > > > > >> > > > > > > > > > > > ID > >>> > > > > > > > >> > > > > > > > > > > > > is > >>> > > > > > > > >> > > > > > > > > > > > > > > for > >>> > > > > > > > >> > > > > > > > > > > > > > > > after complete. The > >>> reason why > >>> > > we > >>> > > > > need > >>> > > > > > > two > >>> > > > > > > > >> > > separate > >>> > > > > > > > >> > > > > > > > (tagged) > >>> > > > > > > > >> > > > > > > > > > > fields > >>> > > > > > > > >> > > > > > > > > > > > > is > >>> > > > > > > > >> > > > > > > > > > > > > > > for > >>> > > > > > > > >> > > > > > > > > > > > > > > > backwards compatibility. > >>> We > >>> > need > >>> > > > to > >>> > > > > > keep > >>> > > > > > > > the > >>> > > > > > > > >> > same > >>> > > > > > > > >> > > > > > > semantics > >>> > > > > > > > >> > > > > > > > > for > >>> > > > > > > > >> > > > > > > > > > > the > >>> > > > > > > > >> > > > > > > > > > > > > > > > non-tagged field in case > >>> we > >>> > > > > downgrade. > >>> > > > > > > > >> > > > > > > > > > > > > > > > > >>> > > > > > > > >> > > > > > > > > > > > > > > > 104. We set the fields > as > >>> we > >>> > do > >>> > > in > >>> > > > > the > >>> > > > > > > > >> > > > transactional > >>> > > > > > > > >> > > > > > > state > >>> > > > > > > > >> > > > > > > > > (as > >>> > > > > > > > >> > > > > > > > > > we > >>> > > > > > > > >> > > > > > > > > > > > > need > >>> > > > > > > > >> > > > > > > > > > > > > > to > >>> > > > > > > > >> > > > > > > > > > > > > > > > do this for > compatibility > >>> -- > >>> > if > >>> > > we > >>> > > > > > > > >> downgrade, > >>> > > > > > > > >> > we > >>> > > > > > > > >> > > > will > >>> > > > > > > > >> > > > > > > only > >>> > > > > > > > >> > > > > > > > > have > >>> > > > > > > > >> > > > > > > > > > > the > >>> > > > > > > > >> > > > > > > > > > > > > > > > non-tagged fields) It > >>> will be > >>> > > the > >>> > > > > old > >>> > > > > > > > >> producer > >>> > > > > > > > >> > ID > >>> > > > > > > > >> > > > and > >>> > > > > > > > >> > > > > > max > >>> > > > > > > > >> > > > > > > > > > epoch. > >>> > > > > > > > >> > > > > > > > > > > > > > > > > >>> > > > > > > > >> > > > > > > > > > > > > > > > Hope this helps. Let me > >>> know > >>> > if > >>> > > > you > >>> > > > > > have > >>> > > > > > > > >> > further > >>> > > > > > > > >> > > > > > > questions. > >>> > > > > > > > >> > > > > > > > > > > > > > > > > >>> > > > > > > > >> > > > > > > > > > > > > > > > Justine > >>> > > > > > > > >> > > > > > > > > > > > > > > > > >>> > > > > > > > >> > > > > > > > > > > > > > > > On Wed, Dec 20, 2023 at > >>> > 3:33 PM > >>> > > > Jun > >>> > > > > > Rao > >>> > > > > > > > >> > > > > > > > > > <j...@confluent.io.invalid > >>> > > > > > > > >> > > > > > > > > > > > > >>> > > > > > > > >> > > > > > > > > > > > > > > wrote: > >>> > > > > > > > >> > > > > > > > > > > > > > > > > >>> > > > > > > > >> > > > > > > > > > > > > > > > > Hi, Justine, > >>> > > > > > > > >> > > > > > > > > > > > > > > > > > >>> > > > > > > > >> > > > > > > > > > > > > > > > > It seems that you have > >>> made > >>> > > some > >>> > > > > > > changes > >>> > > > > > > > >> to > >>> > > > > > > > >> > > > KIP-890 > >>> > > > > > > > >> > > > > > > since > >>> > > > > > > > >> > > > > > > > > the > >>> > > > > > > > >> > > > > > > > > > > > vote. > >>> > > > > > > > >> > > > > > > > > > > > > > In > >>> > > > > > > > >> > > > > > > > > > > > > > > > > particular, we are > >>> changing > >>> > > the > >>> > > > > > format > >>> > > > > > > > of > >>> > > > > > > > >> > > > > > > > > > TransactionLogValue. > >>> > > > > > > > >> > > > > > > > > > > A > >>> > > > > > > > >> > > > > > > > > > > > > few > >>> > > > > > > > >> > > > > > > > > > > > > > > > > comments related to > >>> that. > >>> > > > > > > > >> > > > > > > > > > > > > > > > > > >>> > > > > > > > >> > > > > > > > > > > > > > > > > 100. Just to be clear. > >>> The > >>> > > > > overflow > >>> > > > > > > case > >>> > > > > > > > >> > (i.e. > >>> > > > > > > > >> > > > > when a > >>> > > > > > > > >> > > > > > > new > >>> > > > > > > > >> > > > > > > > > > > > > producerId > >>> > > > > > > > >> > > > > > > > > > > > > > is > >>> > > > > > > > >> > > > > > > > > > > > > > > > > generated) is when the > >>> > current > >>> > > > > epoch > >>> > > > > > > > >> equals > >>> > > > > > > > >> > to > >>> > > > > > > > >> > > > max > >>> > > > > > > > >> > > > > - > >>> > > > > > > > >> > > > > > 1 > >>> > > > > > > > >> > > > > > > > and > >>> > > > > > > > >> > > > > > > > > > not > >>> > > > > > > > >> > > > > > > > > > > > max? > >>> > > > > > > > >> > > > > > > > > > > > > > > > > > >>> > > > > > > > >> > > > > > > > > > > > > > > > > 101. For the "not > epoch > >>> > > > overflow" > >>> > > > > > > case, > >>> > > > > > > > we > >>> > > > > > > > >> > > write > >>> > > > > > > > >> > > > > the > >>> > > > > > > > >> > > > > > > > > previous > >>> > > > > > > > >> > > > > > > > > > > ID > >>> > > > > > > > >> > > > > > > > > > > > in > >>> > > > > > > > >> > > > > > > > > > > > > > the > >>> > > > > > > > >> > > > > > > > > > > > > > > > > tagged field in the > >>> complete > >>> > > > > phase. > >>> > > > > > Do > >>> > > > > > > > we > >>> > > > > > > > >> > need > >>> > > > > > > > >> > > to > >>> > > > > > > > >> > > > > do > >>> > > > > > > > >> > > > > > > that > >>> > > > > > > > >> > > > > > > > > > since > >>> > > > > > > > >> > > > > > > > > > > > > > produce > >>> > > > > > > > >> > > > > > > > > > > > > > > > id > >>> > > > > > > > >> > > > > > > > > > > > > > > > > doesn't change in this > >>> case? > >>> > > > > > > > >> > > > > > > > > > > > > > > > > > >>> > > > > > > > >> > > > > > > > > > > > > > > > > 102. It seems that the > >>> > meaning > >>> > > > for > >>> > > > > > the > >>> > > > > > > > >> > > > > > > > > > ProducerId/ProducerEpoch > >>> > > > > > > > >> > > > > > > > > > > > > > fields > >>> > > > > > > > >> > > > > > > > > > > > > > > in > >>> > > > > > > > >> > > > > > > > > > > > > > > > > TransactionLogValue > >>> changes > >>> > > > > > depending > >>> > > > > > > on > >>> > > > > > > > >> the > >>> > > > > > > > >> > > > > > > > > > TransactionStatus. > >>> > > > > > > > >> > > > > > > > > > > > > When > >>> > > > > > > > >> > > > > > > > > > > > > > > > > the TransactionStatus > is > >>> > > > ongoing, > >>> > > > > > they > >>> > > > > > > > >> > > represent > >>> > > > > > > > >> > > > > the > >>> > > > > > > > >> > > > > > > > > current > >>> > > > > > > > >> > > > > > > > > > > > > > ProducerId > >>> > > > > > > > >> > > > > > > > > > > > > > > > and > >>> > > > > > > > >> > > > > > > > > > > > > > > > > the current > >>> ProducerEpoch. > >>> > > When > >>> > > > > the > >>> > > > > > > > >> > > > > TransactionStatus > >>> > > > > > > > >> > > > > > > is > >>> > > > > > > > >> > > > > > > > > > > > > > > > > > >>> PrepareCommit/PrepareAbort, > >>> > > they > >>> > > > > > > > represent > >>> > > > > > > > >> > the > >>> > > > > > > > >> > > > > > current > >>> > > > > > > > >> > > > > > > > > > > ProducerId > >>> > > > > > > > >> > > > > > > > > > > > > and > >>> > > > > > > > >> > > > > > > > > > > > > > > the > >>> > > > > > > > >> > > > > > > > > > > > > > > > > next ProducerEpoch. > >>> When the > >>> > > > > > > > >> > TransactionStatus > >>> > > > > > > > >> > > is > >>> > > > > > > > >> > > > > > > > > > Commit/Abort, > >>> > > > > > > > >> > > > > > > > > > > > > they > >>> > > > > > > > >> > > > > > > > > > > > > > > > > further depend on > >>> whether > >>> > the > >>> > > > > epoch > >>> > > > > > > > >> overflows > >>> > > > > > > > >> > > or > >>> > > > > > > > >> > > > > not. > >>> > > > > > > > >> > > > > > > If > >>> > > > > > > > >> > > > > > > > > > there > >>> > > > > > > > >> > > > > > > > > > > is > >>> > > > > > > > >> > > > > > > > > > > > > no > >>> > > > > > > > >> > > > > > > > > > > > > > > > > overflow, they > represent > >>> > the > >>> > > > > > current > >>> > > > > > > > >> > > ProducerId > >>> > > > > > > > >> > > > > and > >>> > > > > > > > >> > > > > > > the > >>> > > > > > > > >> > > > > > > > > next > >>> > > > > > > > >> > > > > > > > > > > > > > > > ProducerEpoch > >>> > > > > > > > >> > > > > > > > > > > > > > > > > (max). Otherwise, they > >>> > > represent > >>> > > > > the > >>> > > > > > > > newly > >>> > > > > > > > >> > > > > generated > >>> > > > > > > > >> > > > > > > > > > ProducerId > >>> > > > > > > > >> > > > > > > > > > > > > and a > >>> > > > > > > > >> > > > > > > > > > > > > > > > > ProducerEpoch of 0. Is > >>> that > >>> > > > right? > >>> > > > > > > This > >>> > > > > > > > >> seems > >>> > > > > > > > >> > > not > >>> > > > > > > > >> > > > > > easy > >>> > > > > > > > >> > > > > > > to > >>> > > > > > > > >> > > > > > > > > > > > > understand. > >>> > > > > > > > >> > > > > > > > > > > > > > > > Could > >>> > > > > > > > >> > > > > > > > > > > > > > > > > we provide some > examples > >>> > like > >>> > > > what > >>> > > > > > > Artem > >>> > > > > > > > >> has > >>> > > > > > > > >> > > done > >>> > > > > > > > >> > > > > in > >>> > > > > > > > >> > > > > > > > > KIP-939? > >>> > > > > > > > >> > > > > > > > > > > > Have > >>> > > > > > > > >> > > > > > > > > > > > > we > >>> > > > > > > > >> > > > > > > > > > > > > > > > > considered a simpler > >>> design > >>> > > > where > >>> > > > > > > > >> > > > > > > > ProducerId/ProducerEpoch > >>> > > > > > > > >> > > > > > > > > > > always > >>> > > > > > > > >> > > > > > > > > > > > > > > > represent > >>> > > > > > > > >> > > > > > > > > > > > > > > > > the same value (e.g. > >>> for the > >>> > > > > current > >>> > > > > > > > >> > > transaction) > >>> > > > > > > > >> > > > > > > > > independent > >>> > > > > > > > >> > > > > > > > > > > of > >>> > > > > > > > >> > > > > > > > > > > > > the > >>> > > > > > > > >> > > > > > > > > > > > > > > > > TransactionStatus and > >>> epoch > >>> > > > > > overflow? > >>> > > > > > > > >> > > > > > > > > > > > > > > > > > >>> > > > > > > > >> > > > > > > > > > > > > > > > > 103. It's not clear to > >>> me > >>> > why > >>> > > we > >>> > > > > > need > >>> > > > > > > 3 > >>> > > > > > > > >> > fields: > >>> > > > > > > > >> > > > > > > > ProducerId, > >>> > > > > > > > >> > > > > > > > > > > > > > > > PrevProducerId, > >>> > > > > > > > >> > > > > > > > > > > > > > > > > NextProducerId. Could > we > >>> > just > >>> > > > have > >>> > > > > > > > >> ProducerId > >>> > > > > > > > >> > > and > >>> > > > > > > > >> > > > > > > > > > > NextProducerId? > >>> > > > > > > > >> > > > > > > > > > > > > > > > > > >>> > > > > > > > >> > > > > > > > > > > > > > > > > 104. For > >>> > > WriteTxnMarkerRequests, > >>> > > > > if > >>> > > > > > > the > >>> > > > > > > > >> > > producer > >>> > > > > > > > >> > > > > > epoch > >>> > > > > > > > >> > > > > > > > > > > overflows, > >>> > > > > > > > >> > > > > > > > > > > > > > what > >>> > > > > > > > >> > > > > > > > > > > > > > > do > >>> > > > > > > > >> > > > > > > > > > > > > > > > > we set the producerId > >>> and > >>> > the > >>> > > > > > > > >> producerEpoch? > >>> > > > > > > > >> > > > > > > > > > > > > > > > > > >>> > > > > > > > >> > > > > > > > > > > > > > > > > Thanks, > >>> > > > > > > > >> > > > > > > > > > > > > > > > > > >>> > > > > > > > >> > > > > > > > > > > > > > > > > Jun > >>> > > > > > > > >> > > > > > > > > > > > > > > > > > >>> > > > > > > > >> > > > > > > > > > > > > > > > > >>> > > > > > > > >> > > > > > > > > > > > > > > > > >>> > > > > > > > >> > > > > > > > > > > > > > > > > >>> > > > > > > > >> > > > > > > > > > > > > > > > >>> > > > > > > > >> > > > > > > > > > > > > > > >>> > > > > > > > >> > > > > > > > > > > > > > >>> > > > > > > > >> > > > > > > > > > > > > >>> > > > > > > > >> > > > > > > > > > > > >>> > > > > > > > >> > > > > > > > > > > >>> > > > > > > > >> > > > > > > > > > >>> > > > > > > > >> > > > > > > > > >>> > > > > > > > >> > > > > > > > >>> > > > > > > > >> > > > > > > >>> > > > > > > > >> > > > > > >>> > > > > > > > >> > > > > >>> > > > > > > > >> > > > >>> > > > > > > > >> > > >>> > > > > > > > >> > >>> > > > > > > > > > >>> > > > > > > > > >>> > > > > > > > >>> > > > > > > >>> > > > > > >>> > > > > >>> > > > >>> > > >>> > >> >
