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From benjamin roth <brs...@gmail.com>
Subject Re: Customize Cassandra to execute a query multiple times
Date Thu, 27 Jul 2017 07:49:14 GMT
+1

2017-07-27 9:26 GMT+02:00 Marco Massenzio <m.massenzio@gmail.com>:

> Why not simply have a microservice that does this for you?
>
> It may expose an API that allows to either store queries and/or conditions
> that trigger the queries (maybe time elapsed, an alert generated,
> whatever...) and it would then connect to Cassandra and execute the stored
> query(ies).
>
> Given that there is no client waiting for a response, then latency is not
> even a (major) issue, so the extra network hop is probably of little
> consequence.
>
> Why would you want this to be an integral part of Cassandra?
> (like Jeff I also am struggling to come up with a concrete use case where
> this would be desirable)
>
> --
> *Marco Massenzio*
> http://codetrips.com
>
> On Wed, Jul 26, 2017 at 11:06 PM, Ke Wang <klwangke@gmail.com> wrote:
>
> > 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 <jjirsa@apache.org>:
> >
> > >
> > >
> > > On 2017-07-26 22:19 (-0700), Ke Wang <klwangke@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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> > >
> > >
> >
>

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