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From "Benjamin Lerer (JIRA)" <j...@apache.org>
Subject [jira] [Resolved] (CASSANDRA-14323) Same timestamp insert conflict resolution breaks row-level data consistency
Date Tue, 20 Mar 2018 08:49:00 GMT

     [ https://issues.apache.org/jira/browse/CASSANDRA-14323?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Benjamin Lerer resolved CASSANDRA-14323.
----------------------------------------
       Resolution: Won't Fix
    Reproduced In: 3.11.2, 2.1.13  (was: 2.1.13, 3.11.2)

> Same timestamp insert conflict resolution breaks row-level data consistency
> ---------------------------------------------------------------------------
>
>                 Key: CASSANDRA-14323
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-14323
>             Project: Cassandra
>          Issue Type: Bug
>          Components: Core
>            Reporter: Rishi Kathera
>            Priority: Minor
>
> When inserting multiple rows with the same primary key and timestamp, memtable update
logic does not maintain row-level consistency for the key inserted. For example,
> {code:java}
> create table test.consistency(pk int PRIMARY KEY , nk1 text, nk2 text);
> BEGIN UNLOGGED BATCH USING TIMESTAMP 1521080773000 
> insert into test.consistency (pk,nk1,nk2) VALUES (2,'nk1','nk2'); 
> insert into test.consistency (pk,nk1,nk2) VALUES (2,'nk2','nk1'); 
> APPLY BATCH; 
> select * from test.consistency;
> {code}
> In this case, I would expect either one row overwrites the other so the result of the
read would be either
> {code:java}
> 2, nk1, nk2{code}
> or
> {code:java}
> 2, nk2, nk1{code}
> but the row retrieved is
> {code:java}
> 2, nk2, nk2{code}
>  which breaks consistency of the writes. This behavior comes from this logic, 
> [https://github.com/apache/cassandra/blob/trunk/src/java/org/apache/cassandra/db/Conflicts.java#L45]
> where it appears that the value of the cell itself is used to resolve overwrite conflict
which I don't think is the correct way of handling the situation. Shouldn't it either be
overwrite or not overwrite for all cases?



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