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From: Alain RODRIGUEZ <arodrime@gmail.com>
Date: Thu, 17 Mar 2016 11:37:55 +0100
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 <CA+VSrLoiYWA_f+MCdwbKh1rLc3tvNWWHuVQYdPaYwuycQC0Q7g@mail.gmail.com>
Subject: Re: Read consistency
To: user@cassandra.apache.org
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Hi Arko,

Never used that consistency level so far, but here is some information:
http://docs.datastax.com/en/cassandra/2.0/cassandra/dml/dml_tunable_consistency_c.html

Cassandra 2.0 uses the Paxos consensus protocol, which resembles 2-phase
> commit, to support linearizable consistency. All operations are
> *quorum-based* and updates will incur a performance hit, effectively a
> degradation to one-third of normal. For in-depth information about this new
> consistency level, see the article,*Lightweight transactions in Cassandra*
> <http://www.datastax.com/dev/blog/lightweight-transactions-in-cassandra-2-0>
> .


 So it appears that a read using quorum should be fine (remember to use
local consistency level on a multi-DC environment if this is what you want
to do).

Never checked that on my own, just read that, fwiw.

C*heers,
-----------------------
Alain Rodriguez - alain@thelastpickle.com
France

The Last Pickle - Apache Cassandra Consulting
http://www.thelastpickle.com

2016-03-16 2:43 GMT+01:00 Arko Provo Mukherjee <arkoprovomukherjee@gmail.com
>:

> Hello,
>
> I am designing a system where for a situation, I need to have SERIAL
> consistency during writes.
>
> I understand that if the write was with QUORUM, a Read with QUORUM would
> have fetched me the correct (most recent) data.
>
> My question is what is the minimum consistency level required for read,
> when my write consistency is SERIAL.
>
> Any pointers would be much appreciated.
>
> Thanks & regards
> Arko
>
>

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<div dir=3D"ltr">Hi Arko,<div><br></div><div>Never used that consistency le=
vel so far, but here is some information:=C2=A0<a href=3D"http://docs.datas=
tax.com/en/cassandra/2.0/cassandra/dml/dml_tunable_consistency_c.html">http=
://docs.datastax.com/en/cassandra/2.0/cassandra/dml/dml_tunable_consistency=
_c.html</a></div><div><br></div><blockquote class=3D"gmail_quote" style=3D"=
margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,20=
4,204);border-left-style:solid;padding-left:1ex"><span style=3D"color:rgb(5=
5,76,81);font-family:HelveticaNeueLTStd-Roman,Helvetica,Arial,sans-serif;fo=
nt-size:14px">Cassandra 2.0 uses the Paxos consensus protocol, which resemb=
les 2-phase commit, to support linearizable consistency. All operations are=
 <b>quorum-based</b> and updates will incur a performance hit, effectively =
a degradation to one-third of normal. For in-depth information about this n=
ew consistency level, see the article,</span><a class=3D"" href=3D"http://w=
ww.datastax.com/dev/blog/lightweight-transactions-in-cassandra-2-0" target=
=3D"_blank" style=3D"color:rgb(0,122,151);text-decoration:none;font-family:=
HelveticaNeueLTStd-Roman,Helvetica,Arial,sans-serif;font-size:14px;backgrou=
nd-image:initial;background-repeat:initial"><em class=3D"">Lightweight tran=
sactions in Cassandra</em></a><span style=3D"color:rgb(55,76,81);font-famil=
y:HelveticaNeueLTStd-Roman,Helvetica,Arial,sans-serif;font-size:14px">.</sp=
an></blockquote><div><br></div><div>=C2=A0So it appears that a read using q=
uorum should be fine (remember to use local consistency level on a multi-DC=
 environment if this is what you want to do).</div><div><br></div><div>Neve=
r checked that on my own, just read that, fwiw.</div><div><br></div><div>C*=
heers,</div><div><div>-----------------------</div><div>Alain Rodriguez - <=
a href=3D"mailto:alain@thelastpickle.com">alain@thelastpickle.com</a></div>=
<div>France</div><div><br></div><div>The Last Pickle - Apache Cassandra Con=
sulting</div><div><a href=3D"http://www.thelastpickle.com">http://www.thela=
stpickle.com</a></div></div></div><div class=3D"gmail_extra"><br><div class=
=3D"gmail_quote">2016-03-16 2:43 GMT+01:00 Arko Provo Mukherjee <span dir=
=3D"ltr">&lt;<a href=3D"mailto:arkoprovomukherjee@gmail.com" target=3D"_bla=
nk">arkoprovomukherjee@gmail.com</a>&gt;</span>:<br><blockquote class=3D"gm=
ail_quote" style=3D"margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-le=
ft:1ex"><div dir=3D"ltr">Hello,<div><br></div><div>I am designing a system =
where for a situation, I need to have SERIAL consistency during writes.</di=
v><div><br></div><div>I understand that if the write was with QUORUM, a Rea=
d with QUORUM would have fetched me the correct (most recent) data.</div><d=
iv><br>My question is what is the minimum consistency level required for re=
ad, when my write consistency is SERIAL.</div><div><br></div><div>Any point=
ers would be much appreciated.=C2=A0</div><div><br></div><div>Thanks &amp; =
regards</div><span class=3D"HOEnZb"><font color=3D"#888888"><div>Arko</div>=
<div><br></div></font></span></div>
</blockquote></div><br></div>

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