Mailing-List: contact user-help@cassandra.apache.org; run by ezmlm
Precedence: bulk
Reply-To: user@cassandra.apache.org
Received-SPF: neutral (athena.apache.org: 209.85.210.48 is neither permitted
 nor denied by domain of tamar@tok-media.com)
MIME-Version: 1.0
From: Tamar Fraenkel <tamar@tok-media.com>
Date: Wed, 14 Mar 2012 13:32:47 +0200
Message-ID: 
 <CABZP+MThkC37Ee35JGEuZ75P3exN8Mtqd9n0jnCMROEGA5fqxA@mail.gmail.com>
Subject: counter columns question
To: cassandra-user@incubator.apache.org
Content-Type: multipart/related; boundary=047d7b33d630e9af4004bb32567a

--047d7b33d630e9af4004bb32567a
Content-Type: multipart/alternative; boundary=047d7b33d630e9af3e04bb325679

--047d7b33d630e9af3e04bb325679
Content-Type: text/plain; charset=ISO-8859-1

Hi!

My apologies for the naive question, but I am new to Cassandra and even
more to counter columns.

If I have a counter column, what happens if two threads are trying to
increment it's value at the same time for the same key?

Thanks,

*Tamar Fraenkel *
Senior Software Engineer, TOK Media

[image: Inline image 1]

tamar@tok-media.com
Tel:   +972 2 6409736
Mob:  +972 54 8356490
Fax:   +972 2 5612956

--047d7b33d630e9af3e04bb325679
Content-Type: text/html; charset=ISO-8859-1
Content-Transfer-Encoding: quoted-printable

<div dir=3D"ltr">Hi!<div><br></div><div>My=A0apologies=A0for the naive=A0qu=
estion, but I am new to Cassandra and even more to counter columns.</div><d=
iv><br></div><div>If I have a counter column, what happens if two threads a=
re trying to increment it&#39;s value at the same time for the same key?</d=
iv>

<div><br></div><div>Thanks,</div><div><br clear=3D"all"><div dir=3D"ltr"><d=
iv dir=3D"ltr"><b>Tamar Fraenkel=A0</b><br>Senior Software Engineer, TOK Me=
dia=A0<br><br><div dir=3D"ltr"><img src=3D"cid:ii_135b91fb888fa9ff" alt=3D"=
Inline image 1"><br>

<div><br><a href=3D"mailto:tamar@tok-media.com" target=3D"_blank">tamar@tok=
-media.com</a><br>Tel:=A0=A0=A0<a value=3D"+97226409736">+972 2 6409736</a>=
=A0<br>Mob:=A0=A0<a value=3D"+972548356490">+972 54 8356490</a>=A0<br>Fax:=
=A0=A0=A0<a value=3D"+97225612956">+972 2 5612956</a>=A0</div>

</div><br></div><br></div><br>
</div></div>

--047d7b33d630e9af3e04bb325679--

--047d7b33d630e9af4004bb32567a
Content-Type: image/png; name="tokLogo.png"
Content-Transfer-Encoding: base64
Content-ID: <ii_135b91fb888fa9ff>
X-Attachment-Id: ii_135b91fb888fa9ff
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--047d7b33d630e9af4004bb32567a--