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From: "Hiller, Dean" <Dean.Hiller@nrel.gov>
To: "user@cassandra.apache.org" <user@cassandra.apache.org>
Date: Wed, 24 Oct 2012 05:51:51 -0600
Subject: Re: What does ReadRepair exactly do?
Thread-Topic: What does ReadRepair exactly do?
Thread-Index: Ac2x3fUWAYZty4BfTuuIQ4D9NLaVPw==
Message-ID: <CCAD3206.1375F%Dean.Hiller@nrel.gov>
In-Reply-To: <1351040699422-7583355.post@n2.nabble.com>
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Keep in mind, returning the older version is usually fine.  Just imagine
if your user clicked write 1 ms before, then the new version might be
returned.  If he gets the older version and refreshes the page, he gets
the newer version.  Same with an automated program as well=8A.in general it
is okay to get the older or newer value.  If you are reading 2 rows
however instead of one, that may change.

Dean

On 10/23/12 7:04 PM, "shankarpnsn" <shankarpnsn@gmail.com> wrote:

>manuzhang wrote
>> why repair again? We block until the consistency constraint is met. Then
>> the latest version is returned and repair is done asynchronously if any
>> mismatch. We may retry read if fewer columns than required are returned.
>
>Just to make sure I understand you correct, considering the case when a
>read
>repair is in flight and a subsequent write affects one or more of the
>replicas that was scheduled to received the repair mutations. In this
>case,
>are you saying that we return the older version to the user rather than
>the
>latest version that was effected by the write ?
>
>
>
>--
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>-ReadRepair-exactly-do-tp7583261p7583355.html
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