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: > As the use case is of time series data model, TWCS will be give some benefit > (without TTL) and with frequent deleted data > Are there any best practices/recommendations to handle high number of > tombstones > 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 > <mailto: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 >> <mailto: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: >> 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 >> Do we have any other strategy (or combination of strategies) to manage >> frequently deleted time-series data >> Thanks in advance. >> >> Adarsh Kumar
