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Date: Tue, 13 Nov 2012 22:01:29 +0800
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Subject: Re: Read during digest mismatch
From: Manu Zhang <owenzhang1990@gmail.com>
To: user@cassandra.apache.org
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If consistency is two, don't we just send data request to one and digest
request to another?


On Mon, Nov 12, 2012 at 2:49 AM, Jonathan Ellis <jbellis@gmail.com> wrote:

> Correct.  Which is one reason there is a separate setting for
> cross-datacenter read repair, by the way.
>
> On Thu, Nov 8, 2012 at 4:43 PM, sankalp kohli <kohlisankalp@gmail.com>
> wrote:
> > Hi,
> >     Lets say I am reading with consistency TWO and my replication is 3.
> The
> > read is eligible for global read repair. It will send a request to get
> data
> > from one node and a digest request to two.
> > If there is a digest mismatch, what I am reading from the code looks
> like it
> > will get the data from all three nodes and do a resolve of the data
> before
> > returning to the client.
> >
> > Is it correct or I am readind the code wrong?
> >
> > Also if this is correct, look like if the third node is in other DC, the
> > read will slow down even when the consistency was TWO?
> >
> > Thanks,
> > Sankalp
> >
> >
>
>
>
> --
> Jonathan Ellis
> Project Chair, Apache Cassandra
> co-founder of DataStax, the source for professional Cassandra support
> http://www.datastax.com
>

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If consistency is two, don&#39;t we just send data request to one and diges=
t request to another?<div class=3D"gmail_extra"><br><br><div class=3D"gmail=
_quote">On Mon, Nov 12, 2012 at 2:49 AM, Jonathan Ellis <span dir=3D"ltr">&=
lt;<a href=3D"mailto:jbellis@gmail.com" target=3D"_blank">jbellis@gmail.com=
</a>&gt;</span> wrote:<br>
<blockquote class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;border-left:1p=
x #ccc solid;padding-left:1ex">Correct. =A0Which is one reason there is a s=
eparate setting for<br>
cross-datacenter read repair, by the way.<br>
<div class=3D"HOEnZb"><div class=3D"h5"><br>
On Thu, Nov 8, 2012 at 4:43 PM, sankalp kohli &lt;<a href=3D"mailto:kohlisa=
nkalp@gmail.com">kohlisankalp@gmail.com</a>&gt; wrote:<br>
&gt; Hi,<br>
&gt; =A0 =A0 Lets say I am reading with consistency TWO and my replication =
is 3. The<br>
&gt; read is eligible for global read repair. It will send a request to get=
 data<br>
&gt; from one node and a digest request to two.<br>
&gt; If there is a digest mismatch, what I am reading from the code looks l=
ike it<br>
&gt; will get the data from all three nodes and do a resolve of the data be=
fore<br>
&gt; returning to the client.<br>
&gt;<br>
&gt; Is it correct or I am readind the code wrong?<br>
&gt;<br>
&gt; Also if this is correct, look like if the third node is in other DC, t=
he<br>
&gt; read will slow down even when the consistency was TWO?<br>
&gt;<br>
&gt; Thanks,<br>
&gt; Sankalp<br>
&gt;<br>
&gt;<br>
<br>
<br>
<br>
</div></div><span class=3D"HOEnZb"><font color=3D"#888888">--<br>
Jonathan Ellis<br>
Project Chair, Apache Cassandra<br>
co-founder of DataStax, the source for professional Cassandra support<br>
<a href=3D"http://www.datastax.com" target=3D"_blank">http://www.datastax.c=
om</a><br>
</font></span></blockquote></div><br></div>

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