Hi, Damian, I was just wondering if we should disable size-based retention in the compact_and_delete mode. So, it sounds like that there could be a use case for that. Since by default, the size-based retention is infinite, I think we can just leave the KIP as it is.
Thanks, Jun On Fri, Aug 12, 2016 at 12:10 AM, Damian Guy <damian....@gmail.com> wrote: > Hi, > > The only concrete example i can think of is a case for limiting disk usage. > Say, i had something like Connect running that was tracking changes in a > database. Downstream i don't really care about every change, i just want > the latest values, so compaction could be enabled. However, the kafka > cluster has limited disk space so we need to limit the size of each > partition. > In a previous life i have done the same, just without compaction turned on. > > Besides, i don't think it costs us anything in terms of added complexity to > enable it for time & size based retention - the code already does this for > us. > > Thanks, > Damian > > On Fri, 12 Aug 2016 at 05:30 Neha Narkhede <n...@confluent.io> wrote: > > > Jun, > > > > The motivation for this KIP is to handle joins and windows in Kafka > > streams better and since Streams supports time-based windows, the KIP > > suggests combining time-based deletion and compaction. > > > > It might make sense to do the same for size-based windows, but can you > > think of a concrete use case? If not, perhaps we can come back to it. > > On Thu, Aug 11, 2016 at 3:08 PM Jun Rao <j...@confluent.io> wrote: > > > >> Hi, Damian, > >> > >> Thanks for the proposal. It makes sense to use time-based deletion > >> retention and compaction together, as you mentioned in the KStream. > >> > >> Is there a use case where we want to combine size-based deletion > retention > >> and compaction together? > >> > >> Jun > >> > >> On Thu, Aug 11, 2016 at 2:00 AM, Damian Guy <damian....@gmail.com> > wrote: > >> > >> > Hi Jason, > >> > > >> > Thanks for your input - appreciated. > >> > > >> > 1. Would it make sense to use this KIP in the consumer coordinator to > >> > > expire offsets based on the topic's retention time? Currently, we > >> have a > >> > > periodic task which scans the full cache to check which offsets can > be > >> > > expired, but we might be able to get rid of this if we had a > callback > >> to > >> > > update the cache when a segment was deleted. Technically offsets can > >> be > >> > > given their own expiration time, but it seems questionable whether > we > >> > need > >> > > this going forward (the new consumer doesn't even expose it at the > >> > moment). > >> > > > >> > > >> > The KIP in its current form isn't adding a callback. So you'd still > >> need to > >> > scan the cache and remove any expired offsets, however you wouldn't > send > >> > the tombstone messages. > >> > Having a callback sounds useful, though it isn't clear to me how you > >> would > >> > know which offsets to remove from the cache on segment deletion? I > will > >> > look into it. > >> > > >> > > >> > > 2. This KIP could also be useful for expiration in the case of a > cache > >> > > maintained on the client, but I don't see an obvious way that we'd > be > >> > able > >> > > to leverage it since there's no indication to the client when a > >> segment > >> > has > >> > > been deleted (unless they reload the cache from the beginning of the > >> > log). > >> > > One approach I can think of would be to write corresponding > >> tombstones as > >> > > necessary when a segment is removed, but that seems pretty heavy. > Have > >> > you > >> > > considered this problem? > >> > > > >> > > > >> > We've not considered this and I'm not sure we want to as part of this > >> KIP. > >> > > >> > Thanks, > >> > Damian > >> > > >> > > >> > > > >> > > > >> > > On Mon, Aug 8, 2016 at 12:41 AM, Damian Guy <damian....@gmail.com> > >> > wrote: > >> > > > >> > > > Hi, > >> > > > > >> > > > We have created KIP 71: Enable log compaction and deletion to > >> co-exist` > >> > > > > >> > > > https://cwiki.apache.org/confluence/display/KAFKA/KIP- > >> > > > 71%3A+Enable+log+compaction+and+deletion+to+co-exist > >> > > > > >> > > > Please take a look. Feedback is appreciated. > >> > > > > >> > > > Thank you > >> > > > > >> > > > >> > > >> > > >
