Return-Path: X-Original-To: apmail-cassandra-user-archive@www.apache.org Delivered-To: apmail-cassandra-user-archive@www.apache.org Received: from mail.apache.org (hermes.apache.org [140.211.11.3]) by minotaur.apache.org (Postfix) with SMTP id B621718284 for ; Tue, 23 Jun 2015 18:25:13 +0000 (UTC) Received: (qmail 78020 invoked by uid 500); 23 Jun 2015 18:25:11 -0000 Delivered-To: apmail-cassandra-user-archive@cassandra.apache.org Received: (qmail 77986 invoked by uid 500); 23 Jun 2015 18:25:10 -0000 Mailing-List: contact user-help@cassandra.apache.org; run by ezmlm Precedence: bulk List-Help: List-Unsubscribe: List-Post: List-Id: Reply-To: user@cassandra.apache.org Delivered-To: mailing list user@cassandra.apache.org Received: (qmail 77976 invoked by uid 99); 23 Jun 2015 18:25:10 -0000 Received: from Unknown (HELO spamd4-us-west.apache.org) (209.188.14.142) by apache.org (qpsmtpd/0.29) with ESMTP; Tue, 23 Jun 2015 18:25:10 +0000 Received: from localhost (localhost [127.0.0.1]) by spamd4-us-west.apache.org (ASF Mail Server at spamd4-us-west.apache.org) with ESMTP id 7BD43C12D1 for ; Tue, 23 Jun 2015 18:25:10 +0000 (UTC) X-Virus-Scanned: Debian amavisd-new at spamd4-us-west.apache.org X-Spam-Flag: NO X-Spam-Score: 2.88 X-Spam-Level: ** X-Spam-Status: No, score=2.88 tagged_above=-999 required=6.31 tests=[DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, HTML_MESSAGE=3, RCVD_IN_MSPIKE_H3=-0.01, RCVD_IN_MSPIKE_WL=-0.01, SPF_PASS=-0.001, URIBL_BLOCKED=0.001] autolearn=disabled Authentication-Results: spamd4-us-west.apache.org (amavisd-new); dkim=pass (2048-bit key) header.d=gmail.com Received: from mx1-us-east.apache.org ([10.40.0.8]) by localhost (spamd4-us-west.apache.org [10.40.0.11]) (amavisd-new, port 10024) with ESMTP id GeX6nv-vP4MF for ; Tue, 23 Jun 2015 18:25:00 +0000 (UTC) Received: from mail-la0-f41.google.com (mail-la0-f41.google.com [209.85.215.41]) by mx1-us-east.apache.org (ASF Mail Server at mx1-us-east.apache.org) with ESMTPS id CF1FE4C0E0 for ; Tue, 23 Jun 2015 18:24:59 +0000 (UTC) Received: by lagx9 with SMTP id x9so11963661lag.1 for ; Tue, 23 Jun 2015 11:24:13 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :content-type; bh=dR3BTr9GO4MnGshIWWOpYLAuc9+Kt4aw/wrSDnpgc8A=; b=Q1KCv4ZyRAkWCPLcmDAW+KvtIa/GngT1cQtG/CiEsASjBxwArG1eMH8YevpV2iWBQ2 +gx7iKoP1VfeCQt6mTWPGWHBAVWErtbkrS08vFqdGOvzkyFIgkV6074F5Wu6CgL8C9nO fG9AxGJI8yU7rUS7Cx80RegYAYOEwOfEQbQKsNVgr91u3B5i6dARZMx2GaZXRcMYvsGy CzJMXe4LMitBlD8iNulgqhW2LI/E/odRNXtXegiMa1u4DKJBiQ+gck1//ZGdUaHBhY9s 7KjCOo5VzcwmpgK/N+yP509hNVFfcqP3kApGLhmHx0YuaeiwtwmjGUF106XkF8xkYYzF MLRA== X-Received: by 10.112.180.201 with SMTP id dq9mr37381082lbc.78.1435083853761; Tue, 23 Jun 2015 11:24:13 -0700 (PDT) MIME-Version: 1.0 Received: by 10.112.198.106 with HTTP; Tue, 23 Jun 2015 11:23:54 -0700 (PDT) In-Reply-To: References: <1435083416.15044.YahooMailAndroidMobile@web192906.mail.sg3.yahoo.com> From: Alain RODRIGUEZ Date: Tue, 23 Jun 2015 20:23:54 +0200 Message-ID: Subject: Re: Read Consistency To: user@cassandra.apache.org Content-Type: multipart/alternative; boundary=001a11c345c05394270519337ffd --001a11c345c05394270519337ffd Content-Type: text/plain; charset=UTF-8 Btw, Hope you'll find the answers you could not ask in today online lesson ;-). C*heers 2015-06-23 20:22 GMT+02:00 Alain RODRIGUEZ : > Hi, > > I do not agree with Scenario 1 result Arun, > > The 2 nodes don't have the data yet are available. IMHO what happens next > i a slow read since it will have to perform read repair and coordinator > will send back the result and an 'OK' message.Consistency is not met when > nor enough nodes were up. > > Agreed on scenario 2. I would add that one repair will be synchronous and > mandatory while the second depends on your read repair chance parameter on > this table and is async. > > C*heers > > 2015-06-23 20:16 GMT+02:00 Anuj Wadehra : > >> Why would it fail and with what Thrift error? What if the data didnt >> exist on any of the nodes..query wont fail if doesnt find data.. >> >> Not convinced.. >> >> Sent from Yahoo Mail on Android >> >> ------------------------------ >> *From*:"arun sirimalla" >> *Date*:Tue, 23 Jun, 2015 at 11:39 pm >> *Subject*:Re: Read Consistency >> >> Scenario 1: Read query is fired for a key, data is found on one node and >> not found on other two nodes who are responsible for the token >> corresponding to key. >> >> You read query will fail, as it expects to receive data from 2 nodes with >> RF=3 >> >> >> Scenario 2: Read query is fired and all 3 replicas have different data >> with different timestamps. >> >> Read query will return the data with most recent timestamp and trigger a >> read repair in the backend . >> >> On Tue, Jun 23, 2015 at 10:57 AM, Anuj Wadehra >> wrote: >> >>> Hi, >>> >>> Need to validate my understanding.. >>> >>> RF=3 , Read CL = Quorum >>> >>> What would be returned to the client in following scenarios: >>> >>> Scenario 1: Read query is fired for a key, data is found on one node and >>> not found on other two nodes who are responsible for the token >>> corresponding to key. >>> >>> Options: no data is returned OR data from the only node having data is >>> returned? >>> >>> Scenario 2: Read query is fired and all 3 replicas have different data >>> with different timestamps. >>> >>> Options: data with latest timestamp is returned OR something else??? >>> >>> Thanks >>> Anuj >>> >>> Sent from Yahoo Mail on Android >>> >>> >> >> >> >> -- >> Arun >> > > --001a11c345c05394270519337ffd Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable
Btw, Hope you'll find the answers you could not ask in= today online lesson ;-).

C*heers

2015-06-23 20:22 GMT+02:00 = Alain RODRIGUEZ <arodrime@gmail.com>:
Hi,

I do not agree with S= cenario 1 result Arun,

The 2 nodes don't have = the data yet are available. IMHO what happens next i a slow read since it w= ill have to perform read repair and coordinator will send back the result a= nd an 'OK' message.Consistency is not met when nor enough nodes wer= e up.

Agreed on scenario 2. I would add that one r= epair will be synchronous and mandatory while the second depends on your re= ad repair chance parameter on this table and is async.

=
C*heers

2015-06-23 20:16 GMT+02:00 = Anuj Wadehra <anujw_2003@yahoo.co.in>:
<= tbody><= /tbody>
Why would it fail and with what Thrift error? = What if the data didnt exist on any of the nodes..query wont fail if doesnt= find data..

Not convinced..

S= ent from Yahoo Mail on Android

From:"arun sir= imalla" <a= runsirik@gmail.com>
Date:Tue, 23 Jun, 2015 at 11:39 pm
= Subject:Re: Read Consistency

Scenario 1: Read query is fi= red for a key, data is found on one node and not found on other two nodes w= ho are responsible for the token corresponding to key.

You re= ad query will fail, as it expects to=C2=A0receive=C2=A0data from 2 nodes wi= th RF=3D3
Scenario 2: Read query is fired and all 3 replicas have different data= with different timestamps.

Read query will return the data with most recent ti= mestamp and trigger a read repair in the backend .

On Tue,= Jun 23, 2015 at 10:57 AM, Anuj Wadehra <anujw_2003@yahoo.co.in> wrote:
Hi,

Need to validate my u= nderstanding..

RF=3D3 , Read CL =3D= Quorum

What would be returned to t= he client in following scenarios:

Scenar= io 1: Read query is fired for a key, data is found on one node and not foun= d on other two nodes who are responsible for the token corresponding to key= .

Options: no data is returned OR data from the only node having data is returned?
Scenario 2: Read query is fired and all 3 repli= cas have different data with different timestamps.

Options: data with latest timestamp is returned OR somethin= g else???

Thanks



--
Arun= =C2=A0


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