cassandra-commits mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Sandeep Tata (JIRA)" <j...@apache.org>
Subject [jira] Commented: (CASSANDRA-48) test-and-set
Date Fri, 03 Apr 2009 16:38:13 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-48?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12695481#action_12695481
] 

Sandeep Tata commented on CASSANDRA-48:
---------------------------------------

Say we have 2 processes doing test-and-set.

Read X              Read X
T&S X +1           T&S X+2

The two T&S are routed to A , B, C:

@A T&S X + 1
                            @B T&S X+2
                            @C T&S X+2
                            @A T&S X+2 <------Fail, A already updated X 
@B T&S X+1 <---- fail
@C T&S X+2 <---- fail


X+1 fails, X+2 succeeds.
A contains a bad value that can be repaired by majority read. Any holes ?



> test-and-set
> ------------
>
>                 Key: CASSANDRA-48
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-48
>             Project: Cassandra
>          Issue Type: Improvement
>            Reporter: Jonathan Ellis
>
> Atomic test-and-set insert operation would be nice: "set value to X but only if the current
value is still Y."  This allows a sort of optimistic consistency: perform a GET, then perform
test-and-set with the value of that GET as Y.
> I do not think that this requires strong consistency to be useful.

-- 
This message is automatically generated by JIRA.
-
You can reply to this email to add a comment to the issue online.


Mime
View raw message