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From: Apache Wiki <wikidiffs@apache.org>
To: Apache Wiki <wikidiffs@apache.org>
Date: Fri, 06 Sep 2013 02:23:53 -0000
Message-ID: <20130906022353.17044.16800@eos.apache.org>
Subject: 
 =?utf-8?q?=5BCassandra_Wiki=5D_Trivial_Update_of_=22FAQ=22_by_JonathanEll?=
 =?utf-8?q?is?=
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The "FAQ" page has been changed by JonathanEllis:
https://wiki.apache.org/cassandra/FAQ?action=3Ddiff&rev1=3D161&rev2=3D162

  <<Anchor(clocktie)>>
  =3D=3D What happens if two updates are made with the same timestamp? =3D=
=3D
  =

- Updates must be commutative, since they may arrive in different orders on=
 different replicas.  Thus, in the case of a timestamp tie, Cassandra follo=
ws two rules: first, deletes take precedence over inserts/updates.  Second,=
 if there are two updates, the one with the lexically larger value is selec=
ted.
+ Updates must be commutative, since they may arrive in different orders on=
 different replicas.  As long as Cassandra has a deterministic way to pick =
the winner, the one selected is as valid as any other, and the specifics sh=
ould be treated as an implementation detail.  That said, in the case of a t=
imestamp tie, Cassandra follows two rules: first, deletes take precedence o=
ver inserts/updates.  Second, if there are two updates, the one with the le=
xically larger value is selected.
 =20