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From "Sylvain Lebresne (JIRA)" <j...@apache.org>
Subject [jira] [Resolved] (CASSANDRA-5751) Columns defined as datatype counter will become 'null' after deletion
Date Mon, 15 Jul 2013 07:00:54 GMT

     [ https://issues.apache.org/jira/browse/CASSANDRA-5751?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Sylvain Lebresne resolved CASSANDRA-5751.
-----------------------------------------

    Resolution: Won't Fix

Quoting http://wiki.apache.org/cassandra/Counters (parts about the technical limitation):
{noformat}
Counter removal is intrinsically limited. For instance, if you issue very quickly the sequence
"increment, remove, increment" it is possible for the removal to be lost (if for some reason
the remove happens to be the last received messages). Hence, removal of counters is provided
for definitive removal only, that is when the deleted counter is not increment afterwards.
This holds for row deletion too: if you delete a row of counters, incrementing any counter
in that row (that existed before the deletion) will result in an undetermined behavior. Note
that if you need to reset a counter, one option (that is unfortunately not concurrent safe)
could be to read its value and add -value.
{noformat}

So, we know re-incrementing after a deletion doesn't work as it should, but we don't know
how to fix it with the current counter design.
                
> Columns defined as datatype counter will become 'null' after deletion
> ---------------------------------------------------------------------
>
>                 Key: CASSANDRA-5751
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-5751
>             Project: Cassandra
>          Issue Type: Bug
>          Components: Core
>    Affects Versions: 1.2.4, 1.2.6
>            Reporter: Yangyi Chen
>            Priority: Minor
>
> The following statements should reproduce the problem:
> CREATE TABLE ctrtest (a varchar, ctr counter, PRIMARY KEY(a) );
> update ctrtest set ctr=ctr+1 where a='a';
> delete from ctrtest where a='a';
> update ctrtest set ctr=ctr+1 where a='a'; 
> select * from ctrtest ;
>  a | ctr
> ---+------
>  a | null

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