Thanks Hiro & Jeff

Jeff,

My LWT(Insert if not exists) query is executed in parallel by 6 threads,
with a possibility of collision.
So, all threads may request to write same data on Cassandra tables.

What would you suggest here ?



Hiro,
i am using Datastax Mapper & Accessor for this.
Something similar to this :
https://docs.datastax.com/en/developer/java-driver/3.6/manual/object_mapper/creating/

Do you have a suggestion , how can i verify that my code is actually
setting query consistency?


Thank you for your response.


On Tue, Jul 9, 2019 at 5:30 PM Hiroyuki Yamada <[email protected]> wrote:

> Do you also set SERIAL CONSISTENCY properly ?
>
> https://docs.datastax.com/en/archived/cql/3.3/cql/cql_reference/cqlshSerialConsistency.html
>
> Hiro
>
> On Tue, Jul 9, 2019 at 2:25 PM Jeff Jirsa <[email protected]> wrote:
> >
> > If applied is false it’s not the first write, the value already exists.
> You’ve likely got a concurrency issue app side or you don’t understand the
> concurrent queries you’re issuing to the db
> >
> > On Jul 8, 2019, at 10:08 PM, raman gugnani <[email protected]>
> wrote:
> >
> > Hi Team,
> >
> > Can anyone help on the same.
> >
> > Cassnadra driver says write is not done but eventually write has been
> done.
> >
> > On Mon, 8 Jul 2019 at 12:31, Upasana Sharma <[email protected]>
> wrote:
> >>
> >>
> >> Hi,
> >>
> >> I am using an LWT Insert transaction similar to:
> >>
> >> INSERT INTO table1 (code, id, subpart) VALUES (:code, :id, :subpart) IF
> NOT EXISTS
> >>
> >> With
> >> readConsistency="LOCAL_SERIAL"
> >> writeConsistency="LOCAL_QUORUM"
> >>
> >> Cassandra Driver: 3.6.0
> >> Cassandra Version: Cassandra 3.11.2
> >>
> >>
> >> The problem is that I am getting [applied] false on the first write to
> cassandra.
> >>
> >> I have set retry policy as writeTimes = 0, so no retries are attempted.
> >>
> >> My application logs for reference:
> >>
> >> c-7967981443032352 - [INFO ] 2019-06-18T19:46:16.276Z
> [pool-15-thread-5] CreateService - SubPartition 104
> >> c-7967981443032352 - [INFO ] 2019-06-18T19:46:16.805Z
> [pool-15-thread-5] Repository - Row[false, A, 1, 104]
> >> c-7967981443032352 - [INFO ] 2019-06-18T19:46:16.805Z
> [pool-15-thread-5] CreateService - SubPartition 104 CodeNumber 75191
> DuplicateCodeGenerated A
> >>
> >> This is causing my count of writes to tables to differ from required
> 100000, to 100001, writing extra codes.
> >>
> >> Please guide here.
> >>
> >> --
> >> Regards,
> >> Upasana Sharma
> >
> >
> >
> > --
> > Raman Gugnani
> >
> > 8588892293
> > Principal Engineer
> > ixigo.com
>
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-- 
Regards,
Upasana Sharma

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