Thanks Jeff,

I'm having gcgs set to 10 mins and changed the table ttl also to 5  hours
compared to insert ttl to 4 hours .  Tracing on doesn't show any tombstone
scans for the reads.  And also log doesn't show tombstone scan alerts. Has
the reads are happening 5-8k reads per node during the peak hours it shows
1M tombstone scans count per read.

On Fri, Feb 22, 2019, 11:46 AM Jeff Jirsa <jji...@gmail.com> wrote:

> If all of your data is TTL’d and you never explicitly delete a cell
> without using s TTL, you can probably drop your GCGS to 1 hour (or less).
>
> Which compaction strategy are you using? You need a way to clear out those
> tombstones. There exist tombstone compaction sub properties that can help
> encourage compaction to grab sstables just because they’re full of
> tombstones which will probably help you.
>
>
> --
> Jeff Jirsa
>
>
> On Feb 22, 2019, at 8:37 AM, Kenneth Brotman <kenbrot...@yahoo.com.invalid>
> wrote:
>
> Can we see the histogram?  Why wouldn’t you at times have that many
> tombstones?  Makes sense.
>
>
>
> Kenneth Brotman
>
>
>
> *From:* Rahul Reddy [mailto:rahulreddy1...@gmail.com
> <rahulreddy1...@gmail.com>]
> *Sent:* Thursday, February 21, 2019 7:06 AM
> *To:* user@cassandra.apache.org
> *Subject:* Tombstones in memtable
>
>
>
> We have small table records are about 5k .
>
> All the inserts comes as 4hr ttl and we have table level ttl 1 day and gc
> grace seconds has 3 hours.  We do 5k reads a second during peak load During
> the peak load seeing Alerts for tomstone scanned histogram reaching million.
>
> Cassandra version 3.11.1. Please let me know how can this tombstone scan
> can be avoided in memtable
>
>

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