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https://issues.apache.org/jira/browse/ACCUMULO-1000?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13676013#comment-13676013
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William Slacum commented on ACCUMULO-1000:
------------------------------------------

It seems the implementation Keith gave is for compare and swap, not compare and 
set. This means that my pre-commit check is an equality operation, which may 
not be enough. Once example that's always used is a bank account- when another 
person makes a charge to a bank account, they don't necessarily care that the 
account balance is the same as some initial check (ie, you said you have $100 
but the bank says you have $90), I only care that the amount covered by the 
charged is exists in the bank account (ie, this gumbo cost $50 and you have 
$90, you may pass go).

I think we could hammer in this functionality by using an iterator that checks 
the precondition and returns a boolean- have you thought about how to add in 
that to {{ConditionalMutation}}? 
                
> support compare and set
> -----------------------
>
>                 Key: ACCUMULO-1000
>                 URL: https://issues.apache.org/jira/browse/ACCUMULO-1000
>             Project: Accumulo
>          Issue Type: New Feature
>          Components: client, tserver
>            Reporter: Keith Turner
>            Assignee: Keith Turner
>             Fix For: 1.6.0
>
>         Attachments: ACCUMULO-1000-proposal-01.html, 
> ACCUMULO-1000-proposal-01.txt
>
>
> Add support to mutation for compare and set operations.  This would allow 
> user to specify that a row must contain certain data for a mutation to be 
> applied.

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