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From Alain RODRIGUEZ <arodr...@gmail.com>
Subject Re: Cassandra Tombstone
Date Thu, 20 Jun 2019 10:46:53 GMT
Hello Aneesh,

Reading your message and answers given, I really think this post I wrote
about 3 years ago now (how quickly time goes through...) about tombstone
might be of interest to you:
https://thelastpickle.com/blog/2016/07/27/about-deletes-and-tombstones.html.
Your problem is not related to tombstone I'd say, but the first part of the
post explains how constancy work in Cassandra, and only then takes the case
of deletes/tombstones. This first part might help you solving your current
issue:
https://thelastpickle.com/blog/2016/07/27/about-deletes-and-tombstones.html#cassandra-some-availability-and-consistency-considerations.
I really tried to reason from scratch, even for people whose new to
Cassandra with a very basic knowledge of internals.

For example you'd read still like:

CL.READ  = Consistency Level (CL) used for reads. Basically the number of
> nodes that will have to acknowledge the read for Cassandra to consider it
> successful.
> CL.WRITE = CL used for writes.
> RF             = Replication Factor



CL.READ + CL.WRITE > RF


If what you have is an availability issue, you should just make sure the CL
is lower or equal to the RF and that all nodes are up and responsive.
FWIW, Quorum = RF/2 + 1, thus if RF is 2 and the consistency level for
deletes is quorum (ie "2 / 2 + 1 = 2") , one node down could start breaking
availability (and most probably will) as CL > number of replicas available
for certain partitions.

Reading the rest of the post might be useful while working out the design
of the schema and queries, in particular if you plan to use deletes/TTLs.

I hope that helps,
C*heers,
-----------------------
Alain Rodriguez - alain@thelastpickle.com
France / Spain

The Last Pickle - Apache Cassandra Consulting
http://www.thelastpickle.com

Le mar. 18 juin 2019 à 09:56, Oleksandr Shulgin <
oleksandr.shulgin@zalando.de> a écrit :

> On Tue, Jun 18, 2019 at 8:06 AM ANEESH KUMAR K.M <aneee22@gmail.com>
> wrote:
>
>>
>> I am using Cassandra cluster with 3 nodes which is hosted on AWS. Also we
>> have NodeJS web Application which is on AWS ELB. Now the issue is that,
>> when I add 2 or more servers (nodeJS) in AWS ELB then the delete queries
>> are not working on Cassandra.
>>
>
> Please provide a more concrete description than "not working".  Do you get
> an error?  Which one?  Does it "not working" silently, i.e. w/o an error,
> but you don't observe the expected effect?  How does the delete query look
> like, what is the effect you expect and what do you observe instead?
>
> --
> Alex
>
>

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