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. 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. > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > -- > > > > > > -- Guozhang > > > > > > > > > > > > > > > > > > > > > > > The information contained in this email is strictly > > confidential and > > > for > > > > the use of the addressee only, unless otherwise > indicated. If > > you > > > are not > > > > the intended recipient, please do not read, copy, use or > > disclose to > > > others > > > > this message or any attachment. Please also notify the > sender > > by > > > replying > > > > to this email or by telephone (+44(020 7896 0011) and > then > > delete > > > the email > > > > and any copies of it. Opinions, conclusion (etc) that do > not > > relate > > > to the > > > > official business of this company shall be understood as > > neither > > > given nor > > > > endorsed by it. IG is a trading name of IG Markets > Limited (a > > company > > > > registered in England and Wales, company number > 04008957) and > > IG > > > Index > > > > Limited (a company registered in England and Wales, > company > > number > > > > 01190902). Registered address at Cannon Bridge House, 25 > > Dowgate > > > Hill, > > > > London EC4R 2YA. Both IG Markets Limited (register number > > 195355) > > > and IG > > > > Index Limited (register number 114059) are authorised and > > regulated > > > by the > > > > Financial Conduct Authority. > > > > > > > > > > > > > The information contained in this email is strictly > confidential and > > for > > > the use of the addressee only, unless otherwise indicated. If > you > > are not > > > the intended recipient, please do not read, copy, use or > disclose to > > others > > > this message or any attachment. Please also notify the sender > by > > replying > > > to this email or by telephone (+44(020 7896 0011) and then > delete > > the email > > > and any copies of it. Opinions, conclusion (etc) that do not > relate > > to the > > > official business of this company shall be understood as > neither > > given nor > > > endorsed by it. IG is a trading name of IG Markets Limited (a > company > > > registered in England and Wales, company number 04008957) and > IG > > Index > > > Limited (a company registered in England and Wales, company > number > > > 01190902). Registered address at Cannon Bridge House, 25 > Dowgate > > Hill, > > > London EC4R 2YA. Both IG Markets Limited (register number > 195355) > > and IG > > > Index Limited (register number 114059) are authorised and > regulated > > by the > > > Financial Conduct Authority. > > > > > > > > > The information contained in this email is strictly confidential and > for > > the use of the addressee only, unless otherwise indicated. If you > are not > > the intended recipient, please do not read, copy, use or disclose to > others > > this message or any attachment. Please also notify the sender by > replying > > to this email or by telephone (+44(020 7896 0011) and then delete > the email > > and any copies of it. Opinions, conclusion (etc) that do not relate > to the > > official business of this company shall be understood as neither > given nor > > endorsed by it. IG is a trading name of IG Markets Limited (a company > > registered in England and Wales, company number 04008957) and IG > Index > > Limited (a company registered in England and Wales, company number > > 01190902). Registered address at Cannon Bridge House, 25 Dowgate > Hill, > > London EC4R 2YA. Both IG Markets Limited (register number 195355) > and IG > > Index Limited (register number 114059) are authorised and regulated > by the > > Financial Conduct Authority. > > > > > 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. >
