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From Benyi Wang <bewang.t...@gmail.com>
Subject Re: Is it safe to change RF in this situation?
Date Thu, 08 Sep 2016 21:51:53 GMT
Thanks Hannu,

Unfortunately, we started changing RF from 2 to 3, and did see the empty
result rate is going higher. I assume that  "If the LOCAL_ONE read hit the
new replica which is not there yet, the CQL query will return nothing." Is
my assumption correct?

On Thu, Sep 8, 2016 at 11:49 AM, Hannu Kröger <hkroger@gmail.com> wrote:

> Hi,
>
> If you change RF=2 -> 3 first, the LOCAL_ONE reads might hit the new
> replica which is not there yet. So I would change LOCAL_ONE -> LOCAL_QUORUM
> first and then change the RF and then run the repair. LOCAL_QUORUM is
> effectively ALL in your case (RF=2) if you have just one DC, so you can
> change the batch CL later.
>
> Cheers,
> Hannu
>
> > On 8 Sep 2016, at 14:42, Benyi Wang <bewang.tech@gmail.com> wrote:
> >
> > * I have a keyspace with RF=2;
> > * The client read the table using LOCAL_ONE;
> > * There is a batch job loading data into the tables using ALL.
> >
> > I want to change RF to 3 and both the client and the batch job use
> LOCAL_QUORUM.
> >
> > My question is "Will the client still read the correct data when the
> repair is running at the time my batch job loading is running too?"
> >
> > Or should I change to LOCAL_QUORUM first?
> >
> > Thanks.
>
>

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