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From Adarsh Kumar <>
Subject Re: TWCS and gc_grace_seconds
Date Fri, 18 Oct 2019 13:22:31 GMT
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.

   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
   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 <> 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 <> 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

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