This sounds like a queue pattern, which is typically an anti-pattern for
Cassandra. I would say that it is very difficult to get the access patterns,
tombstones, and everything else lined up properly to solve a queue problem.
Sean Durity
From: Abhishek Singh <abh23...@gmail.com>
Sent: Tuesday, June 19, 2018 10:41 AM
To: user@cassandra.apache.org
Subject: [EXTERNAL] Re: Tombstone
The Partition key is made of datetime(basically date
truncated to hour) and bucket.I think your RCA may be correct since we are
deleting the partition rows one by one not in a batch files maybe overlapping
for the particular partition.A scheduled thread picks the rows for a partition
based on current datetime and bucket number and checks whether for each row the
entiry is past due or not, if yes we trigger a event and remove the entry.
On Tue 19 Jun, 2018, 7:58 PM Jeff Jirsa,
<jji...@gmail.com<mailto:jji...@gmail.com>> wrote:
The most likely explanation is tombstones in files that won’t be collected as
they potentially overlap data in other files with a lower timestamp (especially
true if your partition key doesn’t change and you’re writing and deleting data
within a partition)
--
Jeff Jirsa
> On Jun 19, 2018, at 3:28 AM, Abhishek Singh
> <abh23...@gmail.com<mailto:abh23...@gmail.com>> wrote:
>
> Hi all,
> We using Cassandra for storing events which are time series based
> for batch processing once a particular batch based on hour is processed we
> delete the entries but we were left with almost 18% deletes marked as
> Tombstones.
> I ran compaction on the particular CF tombstone didn't come
> down.
> Can anyone suggest what is the optimal tunning/recommended
> practice used for compaction strategy and GC_grace period with 100k entries
> and deletes every hour.
>
> Warm Regards
> Abhishek Singh
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