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 >> >> >
