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From: Dikang Gu <dikang85@gmail.com>
Date: Thu, 8 Jun 2017 19:28:56 -0700
Message-ID: <CAPw3+Dh2g24ccOnjPHaV2R58Y=2cR6vvisTvjRfeLZdjoh-5Ww@mail.gmail.com>
Subject: Definition of QUORUM consistency level
To: cassandra <user@cassandra.apache.org>, dev@cassandra.apache.org
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archived-at: Fri, 09 Jun 2017 02:29:23 -0000

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Hello there,

We have some use cases are doing consistent read/write requests, and we
have 4 replicas in that cluster, according to our setup.

What's interesting to me is that, for both read and write quorum requests,
they are blocked for 4/2+1 = 3 replicas, so we are accessing 3 (for write)
+ 3 (for reads) = 6 replicas in quorum requests, which is 2 replicas more
than 4.

I think it's not necessary to have 2 overlap nodes in even replication
factor case.

I suggest to change the `quorumFor(keyspace)` code, separate the case for
read and write requests, so that we can reduce one replica request in read
path.

Any concerns?

Thanks!


-- 
Dikang

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<div dir=3D"ltr"><div>Hello there,</div><div><br></div><div>We have some us=
e cases are doing consistent read/write requests, and we have 4 replicas in=
 that cluster, according to our setup.</div><div><br></div><div>What&#39;s =
interesting to me is that, for both read and write quorum requests, they ar=
e blocked for 4/2+1 =3D 3 replicas, so we are accessing 3 (for write) + 3 (=
for reads) =3D 6 replicas in quorum requests, which is 2 replicas more than=
 4.</div><div><br></div><div>I think it&#39;s not necessary to have 2 overl=
ap nodes in even replication factor case.=C2=A0</div><div><br></div><div>I =
suggest to change the `quorumFor(keyspace)` code, separate the case for rea=
d and write requests, so that we can reduce one replica request in read pat=
h.</div><div><br></div><div>Any concerns?=C2=A0</div><div><br></div><div>Th=
anks!</div><br clear=3D"all"><div><br></div>-- <br><div class=3D"gmail_sign=
ature" data-smartmail=3D"gmail_signature"><div dir=3D"ltr">Dikang<br><div><=
br></div></div></div>
</div>

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