My coworker Radovan wrote up a post on the relationship between gc grace and hinted handoff: https://thelastpickle.com/blog/2018/03/21/hinted-handoff-gc-grace-demystified.html
Jon On Sat, Oct 26, 2019 at 6:45 AM Hossein Ghiyasi Mehr <ghiyasim...@gmail.com> wrote: > It needs to change gc_grace_seconds carefully because it has side effect > on hinted handoff. > > On Fri, Oct 18, 2019 at 5:04 PM Paul Chandler <p...@redshots.com> wrote: > >> Hi Adarsh, >> >> You will have problems if you manually delete data when using TWCS. >> >> To fully understand why, I recommend reading this The Last Pickle post: >> https://thelastpickle.com/blog/2016/12/08/TWCS-part1.html >> And this post I wrote that dives deeper into the problems with deletes: >> http://www.redshots.com/cassandra-twcs-must-have-ttls/ >> >> Thanks >> >> Paul >> >> On 18 Oct 2019, at 14:22, Adarsh Kumar <adarsh0...@gmail.com> wrote: >> >> Thanks Jeff, >> >> >> I just checked with business and we have differences in having TTL. So it >> will be manula purging always. We do not want to use LCS due to high IOs. >> So: >> >> 1. As the use case is of time series data model, TWCS will be give >> some benefit (without TTL) and with frequent deleted data >> 2. Are there any best practices/recommendations to handle high number >> of tombstones >> 3. Can we handle this use case with STCS also (with some >> configurations) >> >> >> Thanks in advance >> >> Adarsh Kumar >> >> On Fri, Oct 18, 2019 at 11:46 AM Jeff Jirsa <jji...@gmail.com> wrote: >> >>> Is everything in the table TTL’d? >>> >>> Do you do explicit deletes before the data is expected to expire ? >>> >>> Generally speaking, gcgs exists to prevent data resurrection. But ttl’d >>> data can’t be resurrected once it expires, so gcgs has no purpose unless >>> you’re deleting it before the ttl expires. If you’re doing that, twcs won’t >>> be able to drop whole sstables anyway, so maybe LCS will be less disk usage >>> (but much higher IO) >>> >>> On Oct 17, 2019, at 10:36 PM, Adarsh Kumar <adarsh0...@gmail.com> wrote: >>> >>> >>> Hi, >>> >>> We have a use case of time series data with TTL where we want to use >>> TimeWindowCompactionStrategy because of its better management for TTL and >>> tombstones. In this case, data we have is frequently deleted so we want to >>> reduce gc_grace_seconds to reduce the tombstones' life and reduce pressure >>> on storage. I have following questions: >>> >>> 1. Do we always need to run repair for the table in reduced >>> gc_grace_seconds or there is any other way to manage repairs in this vase >>> 2. Do we have any other strategy (or combination of strategies) to >>> manage frequently deleted time-series data >>> >>> Thanks in advance. >>> >>> Adarsh Kumar >>> >>> >>
