Re: Customize Cassandra to execute a query multiple times

[Ke Wang]

Hi Jeff,

Thanks for the prompt reply.

I'm sorry I wasn't clear about my use case. Let's say I just want the
server to execute writes that are not directly generated from clients. It
can be previously stored queries (the case in my last email), or it can be
arbitrarily made-up write requests by the server itself.

Can you describe a little bit more on how to implement serializing the
mutation into the table?

Best,
Ke

2017-07-26 22:57 GMT-07:00 Jeff Jirsa <jji...@apache.org>:

>
>
> On 2017-07-26 22:19 (-0700), Ke Wang <klwan...@gmail.com> wrote:
> > Hello all,
> >
> > Is there a way to customize Cassandra to execute a query multiple times?
> >
>
> There's always a way...
>
> > My use case is the following. When the Cassandra server receives queries
> > from remote clients, besides executing those queries, the server also
> > stores the queries. In the future, the server can re-execute stored
> queries
> > under certain circumstances.
> >
>
> Seems like an unusual request. Where are you storing the queries? Are
> these reads or writes? For writes you could just serialize the resulting
> partitionupdate/mutation into a table a la pre-3.0 hints, and then re-play
> as needed (though tbh I don't really get the use case)?
>
>
>
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Customize Cassandra to execute a query multiple times

[Ke Wang]

Hello all,

Is there a way to customize Cassandra to execute a query multiple times?

My use case is the following. When the Cassandra server receives queries
from remote clients, besides executing those queries, the server also
stores the queries. In the future, the server can re-execute stored queries
under certain circumstances.

Currently, when I re-execute a query, I create an internal QueryState
object using: qstate = QueryState forInternalCalls(), and then calls the
request.execute(qstate, queryStartNanoTime); However, the execution seems
to have no effect on the database. There is also no exception message. Does
anyone have a clue on this? Great thanks!

Best,
Ke