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From "Charulata Sharma (charshar)" <chars...@cisco.com>
Subject Re: Lightweight transaction in Multi DC
Date Fri, 08 Sep 2017 22:49:45 GMT
Thanks for your reply. I understand that LOCAL_SERIAL is for within a DC , will setting up
SERIAL not slow down the operation?
And should I set SERIAL for both read and write phase or just Read phase? This is becoming
a big problem for us. It happens for a small percentage of
data set but it happens daily because of the highly concurrent and random DC routing of the
received events.

We had a counter implementation prior to CAS, which used to fail most of the times. CAS provided
a big relief but it is still not totally without errors.
Would really appreciate the community’s feedback.

Thanks,
Charu

From: vasu gunja <vasu.nosql@gmail.com>
Reply-To: "user@cassandra.apache.org" <user@cassandra.apache.org>
Date: Friday, September 8, 2017 at 1:56 PM
To: "user@cassandra.apache.org" <user@cassandra.apache.org>
Subject: Re: Lightweight transaction in Multi DC

LOCAL_SERIAL is dc level, SERIAL checks for complete cluster level.

On Fri, Sep 8, 2017 at 2:33 PM, Charulata Sharma (charshar) <charshar@cisco.com<mailto:charshar@cisco.com>>
wrote:
Yes …it is with LOCAL_SERIAL. Should I be using SERIAL ?

Thanks,
Charu

From: DuyHai Doan <doanduyhai@gmail.com<mailto:doanduyhai@gmail.com>>
Reply-To: "user@cassandra.apache.org<mailto:user@cassandra.apache.org>" <user@cassandra.apache.org<mailto:user@cassandra.apache.org>>
Date: Friday, September 8, 2017 at 12:30 PM
To: "user@cassandra.apache.org<mailto:user@cassandra.apache.org>" <user@cassandra.apache.org<mailto:user@cassandra.apache.org>>
Subject: Re: Lightweight transaction in Multi DC

Are you using CAS with SERIAL consistency level for your multi-DC setup ?

On Fri, Sep 8, 2017 at 9:27 PM, Charulata Sharma (charshar) <charshar@cisco.com<mailto:charshar@cisco.com>>
wrote:
Hi,
      We are facing a serious issue with CAS in a multi DC setup and I wanted to get some
input on it from the forum.

We have a Column family which stores counts for the number of events our application receives.
When the counts reach a certain threshold,
there is another process which kicks in. The issue that is happening is, sometimes when concurrent
events come in 2 Data Centers, both the events read the same count
and increment it to the same value which causes the next process to not kick in.

When concurrent events come in the same DC, this does not happen, because in this case, the
CAS explicitly fails for one of them.
However, in case of Multiple DCs this is not happening. Has anyone faced a similar issue and
is there any resolution to this?? I was unable to find any open Jira on this.

Thanks,
Charu




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