Hi, Dong, Thanks for the update. +1
Jun On Wed, Jan 18, 2017 at 1:44 PM, Dong Lin <lindon...@gmail.com> wrote: > Hi Jun, > > After some more thinking, I agree with you that it is better to simply > throw OffsetOutOfRangeException and not update low_watermark if > offsetToPurge is larger than high_watermark. > > My use-case of allowing low_watermark > high_watermark in 2(b) is to allow > user to purge all the data in the log even if that data is not fully > replicated to followers. An offset higher than high_watermark may be > returned to user either through producer's RecordMetadata, or through > ListOffsetResponse if from_consumer option is false. However, this may > cause problem in case of unclean leader election or when consumer seeks to > the largest offset of the partition. It will complicate this KIP if we were > to address these two problems. > > At this moment I prefer to keep this KIP simple by requiring low_watermark > <= high_watermark. The caveat is that if user does want to purge *all* the > data that is already produced, then he needs to stop all producers that are > producing into this topic, wait long enough for all followers to catch up, > and then purge data using the latest offset of this partition, i.e. > high_watermark. We can revisit this if some strong use-case comes up in the > future. > > I also updated the KIP to allow user to use offset -1L to indicate > high_watermark in the PurgeRequest. In the future we can allow users to use > offset -2L to indicate that they want to purge all data up to logEndOffset. > > Thanks! > Dong > > > On Wed, Jan 18, 2017 at 10:37 AM, Jun Rao <j...@confluent.io> wrote: > > > Hi, Dong, > > > > For 2(b), it seems a bit weird to allow highWatermark to be smaller than > > lowWatermark. Also, from the consumer's perspective, messages are > available > > only up to highWatermark. What if we simply throw > OffsetOutOfRangeException > > if offsetToPurge is larger than highWatermark? > > > > Thanks, > > > > Jun > > > > On Tue, Jan 17, 2017 at 9:54 PM, Dong Lin <lindon...@gmail.com> wrote: > > > > > Hi Jun, > > > > > > Thank you. Please see my answers below. The KIP is updated to answer > > these > > > questions (see here > > > <https://cwiki.apache.org/confluence/pages/diffpagesbyversion.action? > > > pageId=67636826&selectedPageVersions=5&selectedPageVersions=6> > > > ). > > > > > > 1. Yes, in this KIP we wait for all replicas. This is the same as if > > > producer sends a messge with ack=all and isr=all_replicas. So it seems > > that > > > the comparison is OK? > > > > > > 2. Good point! I haven't thought about the case where the > user-specified > > > offset > logEndOffset. Please see answers below. > > > > > > a) If offsetToPurge < lowWatermark, the first condition > > > of DelayedOperationPurgatory will be satisfied immediately when broker > > > receives PurgeRequest. Broker will send PurgeResponse to admin client > > > immediately. The response maps this partition to the lowWatermark. > > > > > > This case is covered as the first condition of > DelayedOperationPurgatory > > in > > > the current KIP. > > > > > > b) If highWatermark < offsetToPurge < logEndOffset, leader will send > > > FetchResponse with low_watermark=offsetToPurge. Follower records the > > > offsetToPurge as low_watermark and sends FetchRequest to the leader > with > > > the new low_watermark. Leader will then send PurgeResponse to admin > > client > > > which maps this partition to the new low_watermark. The data in the > range > > > [highWatermark, offsetToPurge] will still be appended from leader to > > > followers but will not be exposed to consumers. And in a short period > of > > > time low_watermark on the follower will be higher than their > > highWatermark. > > > > > > This case is also covered in the current KIP so no change is required. > > > > > > c) If logEndOffset < offsetToPurge, leader will send PurgeResponse to > > admin > > > client immediately. The response maps this partition to > > > OffsetOutOfRangeException. > > > > > > This case is not covered by the current KIP. I just added this as the > > > second condition for the PurgeRequest to be removed from > > > DelayedOperationPurgatory (in the Proposed Change section). Since the > > > PurgeRequest is satisfied immediately when the leader receives it, it > > > actually won't be put into the DelayedOperationPurgatory. > > > > > > 3. Yes, lowWatermark will be used when smallest_offset is used in the > > > ListOffsetRequest. I just updated Proposed Change section to specify > > this. > > > > > > Thanks, > > > Dong > > > > > > On Tue, Jan 17, 2017 at 6:53 PM, Jun Rao <j...@confluent.io> wrote: > > > > > > > Hi, Dong, > > > > > > > > Thanks for the KIP. Looks good overall. Just a few more comments. > > > > > > > > 1."Note that the way broker handles PurgeRequest is similar to how it > > > > handles ProduceRequest with ack = -1 and isr=all_replicas". It seems > > that > > > > the implementation is a bit different. In this KIP, we wait for all > > > > replicas. But in producer, acks=all means waiting for all in-sync > > > replicas. > > > > > > > > 2. Could you describe the behavior when the specified offsetToPurge > is > > > (a) > > > > smaller than lowWatermark, (b) larger than highWatermark, but smaller > > > than > > > > log end offset, (c) larger than log end offset? > > > > > > > > 3. In the ListOffsetRequest, will lowWatermark be returned when the > > > > smallest_offset option is used? > > > > > > > > Thanks, > > > > > > > > Jun > > > > > > > > > > > > On Wed, Jan 11, 2017 at 1:01 PM, Dong Lin <lindon...@gmail.com> > wrote: > > > > > > > > > Hi all, > > > > > > > > > > It seems that there is no further concern with the KIP-107. At this > > > point > > > > > we would like to start the voting process. The KIP can be found at > > > > > https://cwiki.apache.org/confluence/display/KAFKA/KIP-107 > > > > > %3A+Add+purgeDataBefore%28%29+API+in+AdminClient. > > > > > > > > > > Thanks, > > > > > Dong > > > > > > > > > > > > > > >
