Thanks Jun, let's go with the simple approach (not using attributes) and revise later if we find a compelling reason. I'll update the docs.
-Jason On Tue, Feb 21, 2017 at 6:23 PM, Jun Rao <j...@confluent.io> wrote: > It seems that it's simpler and more consistent to avoid optional keys and > values. Not sure if it's worth squeezing every byte at the expense of > additional complexity. Other than that, +1 from me. > > Also, since this is a large KIP, minor changes may arise as we start the > implementation. It would be good if we can keep the community posted of > those changes, if any. > > Thanks, > > Jun > > On Tue, Feb 21, 2017 at 4:33 PM, Michael Pearce <michael.pea...@ig.com> > wrote: > > > If the argument and objective within this KIP is to keep the overhead of > > the protocol as small as possible and remove redundancy, and every byte > is > > being counted and the introduction of varInts, then it would make sense > to > > use attributes to me. > > > > > > On 22/02/2017, 00:14, "Jason Gustafson" <ja...@confluent.io> wrote: > > > > Done. I've left the key and value as optional since we may not have > > reached > > consensus on whether to use attributes or not. Perhaps we should just > > keep > > it simple and not do it? The benefit seems small. > > > > -Jason > > > > On Tue, Feb 21, 2017 at 4:05 PM, Michael Pearce < > michael.pea...@ig.com > > > > > wrote: > > > > > Ok, no worries, can you add it back ValueLen on this KIP, and > update > > the > > > doc, then we can work from that ☺ > > > > > > Cheers > > > Mike > > > > > > On 22/02/2017, 00:02, "Jason Gustafson" <ja...@confluent.io> > wrote: > > > > > > I feel it was a little odd to leave out the value length > anyway, > > so I > > > would > > > rather add it back and put headers at the end. This is more > > consistent > > > with > > > the rest of the Kafka protocol. > > > > > > -Jason > > > > > > On Tue, Feb 21, 2017 at 3:58 PM, Michael Pearce < > > michael.pea...@ig.com > > > > > > > wrote: > > > > > > > Or we keep as is (valuelen removed), and headers are added > with > > > headers > > > > length.. > > > > > > > > On 21/02/2017, 23:38, "Apurva Mehta" <apu...@confluent.io> > > wrote: > > > > > > > > Right now, we don't need the value length: since it is > the > > last > > > item > > > > in the > > > > message, and we have the message length, we can deduce > the > > value > > > > length. > > > > However, if we are adding record headers to the end, we > > would > > > need to > > > > introduce the value length along with that change. > > > > > > > > On Tue, Feb 21, 2017 at 3:34 PM, Michael Pearce < > > > michael.pea...@ig.com > > > > > > > > > wrote: > > > > > > > > > It seems I cannot add comment on the doc. > > > > > > > > > > In the section around the message protocol. > > > > > > > > > > It has stated: > > > > > > > > > > Message => > > > > > Length => uintVar > > > > > Attributes => int8 > > > > > TimestampDelta => intVar > > > > > OffsetDelta => uintVar > > > > > KeyLen => uintVar [OPTIONAL] > > > > > Key => data [OPTIONAL] > > > > > Value => data [OPTIONAL] > > > > > > > > > > Should it not be: (added missing value len) > > > > > > > > > > Message => > > > > > Length => uintVar > > > > > Attributes => int8 > > > > > TimestampDelta => intVar > > > > > OffsetDelta => uintVar > > > > > KeyLen => uintVar [OPTIONAL] > > > > > Key => data [OPTIONAL] > > > > > ValueLen => uintVar [OPTIONAL] > > > > > Value => data [OPTIONAL] > > > > > > > > > > > > > > > > > > > > On 21/02/2017, 23:07, "Joel Koshy" < > jjkosh...@gmail.com> > > > wrote: > > > > > > > > > > I left a couple of comments/questions directly on > the > > > google-doc > > > > > <https://docs.google.com/document/d/11Jqy_ > > > > > GjUGtdXJK94XGsEIK7CP1SnQGdp2eF0wSw9ra8> > > > > > - I found it much more tractable for a proposal of > > this > > > size to > > > > > discuss in > > > > > context within the doc. The permissions on the doc > > don't > > > let > > > > everyone > > > > > view > > > > > comments, so if there are any material changes that > > come > > > out of > > > > the > > > > > discussions in those comment threads we can > > summarize here. > > > > > > > > > > Thanks, > > > > > > > > > > Joel > > > > > > > > > > On Mon, Feb 20, 2017 at 4:08 PM, Becket Qin < > > > > becket....@gmail.com> > > > > > wrote: > > > > > > > > > > > Thanks for the explanation, Guozhang. That makes > > sense. > > > > > > > > > > > > On Sun, Feb 19, 2017 at 7:28 PM, Guozhang Wang < > > > > wangg...@gmail.com> > > > > > wrote: > > > > > > > > > > > > > Thanks Becket. > > > > > > > > > > > > > > Actually sequence is associated with a message, > > not a > > > > message set. > > > > > For > > > > > > > example if a message set sent by producer > > contains 100 > > > > messages, > > > > > and the > > > > > > > first message's sequence is 5, then the last > > message's > > > > sequence > > > > > number > > > > > > > would be 104, and the next message set's first > > > sequence is > > > > > expected to be > > > > > > > 105. > > > > > > > > > > > > > > > > > > > > > Guozhang > > > > > > > > > > > > > > > > > > > > > On Sun, Feb 19, 2017 at 4:48 PM, Becket Qin < > > > > becket....@gmail.com> > > > > > > wrote: > > > > > > > > > > > > > > > +1. Thanks for the great work on the KIP! > > > > > > > > > > > > > > > > I have only one minor question, in the wiki > > (and the > > > doc) > > > > the new > > > > > > message > > > > > > > > set format has a "FirstSequence" field, > should > > it > > > just be > > > > > "Sequence" if > > > > > > > the > > > > > > > > sequence is always associated with a message > > set? > > > > > > > > > > > > > > > > On Fri, Feb 17, 2017 at 3:28 AM, Michael > > Pearce < > > > > > michael.pea...@ig.com > > > > > > > > > > > > > > > wrote: > > > > > > > > > > > > > > > > > +0 > > > > > > > > > > > > > > > > > > I think need some unified agreement on the > > VarInts. > > > > > > > > > > > > > > > > > > Would this also change in all other area’s > > of the > > > > protocol, > > > > > e.g. > > > > > > value > > > > > > > > and > > > > > > > > > key length in message protocol, to keep > this > > > uniform > > > > across all > > > > > > > protocols > > > > > > > > > going forwards? > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > On 17/02/2017, 00:23, "Apurva Mehta" < > > > > apu...@confluent.io> > > > > > wrote: > > > > > > > > > > > > > > > > > > Hi Jun, > > > > > > > > > > > > > > > > > > Thanks for the reply. Comments inline. > > > > > > > > > > > > > > > > > > On Thu, Feb 16, 2017 at 2:29 PM, Jun > Rao > > < > > > > j...@confluent.io > > > > > > > > > > > > wrote: > > > > > > > > > > > > > > > > > > > Hi, Apurva, > > > > > > > > > > > > > > > > > > > > Thanks for the reply. A couple of > > comment > > > below. > > > > > > > > > > > > > > > > > > > > On Wed, Feb 15, 2017 at 9:45 PM, > Apurva > > > Mehta < > > > > > > > apu...@confluent.io > > > > > > > > > > > > > > > > > > wrote: > > > > > > > > > > > > > > > > > > > > > Hi Jun, > > > > > > > > > > > > > > > > > > > > > > Answers inline: > > > > > > > > > > > > > > > > > > > > > > 210. Pid snapshots: Is the number > of > > pid > > > snapshot > > > > > > configurable > > > > > > > or > > > > > > > > > > hardcoded > > > > > > > > > > > > with 2? When do we decide to roll > > a new > > > > snapshot? > > > > > Based on > > > > > > > > time, > > > > > > > > > byte, > > > > > > > > > > or > > > > > > > > > > > > offset? Is that configurable too? > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > When a replica becomes a follower, we > > do a > > > bit log > > > > > truncation. > > > > > > > > > Having an > > > > > > > > > > older snapshot allows us to recover > the > > > > PID->sequence > > > > > mapping > > > > > > > much > > > > > > > > > quicker > > > > > > > > > > than rescanning the whole log. > > > > > > > > > > > > > > > > > > > > > > > > > > > This is a good point. I have updated > the > > doc > > > with a > > > > more > > > > > detailed > > > > > > > > > proposal. > > > > > > > > > Essentially, snapshots will be created > > on a > > > periodic > > > > > basis. A > > > > > > > > > reasonable > > > > > > > > > period would be every 30 or 60 seconds. > > We > > > will keep > > > > at > > > > > most 2 > > > > > > > copies > > > > > > > > > of > > > > > > > > > the snapshot file. With this setup, we > > would > > > have to > > > > > replay at > > > > > > most > > > > > > > > 60 > > > > > > > > > or > > > > > > > > > 120 seconds of the log in the event of > > log > > > truncation > > > > > during > > > > > > leader > > > > > > > > > failover. > > > > > > > > > > > > > > > > > > If we need to make any of this > > configurable, > > > we can > > > > expose > > > > > a > > > > > > config > > > > > > > > in > > > > > > > > > the > > > > > > > > > future. It would be easier to add a > > config we > > > need > > > > than > > > > > remove > > > > > > one > > > > > > > > with > > > > > > > > > marginal utility. > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > 211. I am wondering if we should > > store > > > > > ExpirationTime in > > > > > > the > > > > > > > > > producer > > > > > > > > > > > > transactionalId mapping message > as > > we do > > > in the > > > > > producer > > > > > > > > > transaction > > > > > > > > > > > status > > > > > > > > > > > > message. If a producer only calls > > > > > initTransactions(), but > > > > > > > never > > > > > > > > > > publishes > > > > > > > > > > > > any data, we still want to be > able > > to > > > expire > > > > and > > > > > remove the > > > > > > > > > producer > > > > > > > > > > > > transactionalId mapping message. > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > Actually, the document was > > inaccurate. The > > > > > transactionalId > > > > > > will > > > > > > > > be > > > > > > > > > > expired > > > > > > > > > > > only if there is no active > > transaction, > > > and the > > > > age of > > > > > the > > > > > > last > > > > > > > > > > transaction > > > > > > > > > > > with that transactionalId is older > > than the > > > > > transactioanlId > > > > > > > > > expiration > > > > > > > > > > > time. With these semantics, storing > > the > > > > expiration > > > > > time in > > > > > > the > > > > > > > > > > > transactionalId mapping message > > won't be > > > useful, > > > > since > > > > > the > > > > > > > > > expiration > > > > > > > > > > time > > > > > > > > > > > is a moving target based on > > transaction > > > activity. > > > > > > > > > > > > > > > > > > > > > > I have updated the doc with a > > > clarification. > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > Currently, the producer > transactionalId > > > mapping > > > > message > > > > > doesn't > > > > > > > > carry > > > > > > > > > > ExpirationTime, but the producer > > transaction > > > status > > > > > message > > > > > > does. > > > > > > > > > It would > > > > > > > > > > be useful if they are consistent. > > > > > > > > > > > > > > > > > > > > > > > > > > > > > You are right. The document has been > > updated to > > > > remove the > > > > > > > > > ExpirationTime > > > > > > > > > from the transaction status messages as > > well. > > > Any > > > > utility > > > > > for > > > > > > this > > > > > > > > > field > > > > > > > > > can be achieved by using the timestamp > > of the > > > message > > > > > itself > > > > > > along > > > > > > > > with > > > > > > > > > another expiration time (like > > transactionalId > > > > expiration > > > > > time, > > > > > > > > > transaction > > > > > > > > > expiration time, etc.). > > > > > > > > > > > > > > > > > > Thanks, > > > > > > > > > Apurva > > > > > > > > > > > > > > > > > > > > > > > > > > > The information contained in this email is > > strictly > > > > > confidential and > > > > > > > for > > > > > > > > > the use of the addressee only, unless > > otherwise > > > > indicated. 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IG is a trading name of IG > > Markets > > > > Limited (a > > > > > company > > > > > > > > > registered in England and Wales, company > > number > > > > 04008957) and > > > > > IG > > > > > > Index > > > > > > > > > Limited (a company registered in England > and > > Wales, > > > > company > > > > > number > > > > > > > > > 01190902). Registered address at Cannon > > Bridge > > > House, 25 > > > > > Dowgate > > > > > > Hill, > > > > > > > > > London EC4R 2YA. 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Both IG Markets Limited (register number > > 195355) > > > and IG > > > > Index Limited (register number 114059) are authorised and > > regulated > > > by the > > > > Financial Conduct Authority. > > > > > > > > > > > > > The information contained in this email is strictly confidential > and > > for > > > the use of the addressee only, unless otherwise indicated. If you > > are not > > > the intended recipient, please do not read, copy, use or disclose > to > > others > > > this message or any attachment. Please also notify the sender by > > replying > > > to this email or by telephone (+44(020 7896 0011) and then delete > > the email > > > and any copies of it. Opinions, conclusion (etc) that do not relate > > to the > > > official business of this company shall be understood as neither > > given nor > > > endorsed by it. IG is a trading name of IG Markets Limited (a > company > > > registered in England and Wales, company number 04008957) and IG > > Index > > > Limited (a company registered in England and Wales, company number > > > 01190902). Registered address at Cannon Bridge House, 25 Dowgate > > Hill, > > > London EC4R 2YA. Both IG Markets Limited (register number 195355) > > and IG > > > Index Limited (register number 114059) are authorised and regulated > > by the > > > Financial Conduct Authority. > > > > > > > > > The information contained in this email is strictly confidential and for > > the use of the addressee only, unless otherwise indicated. If you are not > > the intended recipient, please do not read, copy, use or disclose to > others > > this message or any attachment. Please also notify the sender by replying > > to this email or by telephone (+44(020 7896 0011) and then delete the > email > > and any copies of it. Opinions, conclusion (etc) that do not relate to > the > > official business of this company shall be understood as neither given > nor > > endorsed by it. IG is a trading name of IG Markets Limited (a company > > registered in England and Wales, company number 04008957) and IG Index > > Limited (a company registered in England and Wales, company number > > 01190902). Registered address at Cannon Bridge House, 25 Dowgate Hill, > > London EC4R 2YA. Both IG Markets Limited (register number 195355) and IG > > Index Limited (register number 114059) are authorised and regulated by > the > > Financial Conduct Authority. > > >
