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https://issues.apache.org/jira/browse/OMID-73?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16115761#comment-16115761
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ASF GitHub Bot commented on OMID-73:
------------------------------------

Github user ohadshacham closed the pull request at:

    https://github.com/apache/incubator-omid/pull/12


> Add Checkpoints and visibility levels
> -------------------------------------
>
>                 Key: OMID-73
>                 URL: https://issues.apache.org/jira/browse/OMID-73
>             Project: Apache Omid
>          Issue Type: New Feature
>            Reporter: Ohad Shacham
>            Assignee: Ohad Shacham
>         Attachments: OMID-73.v1.patch
>
>
> A checkpoint is a point in a transaction where every write occurs after the 
> checkpoint may not be visible by the transaction. 
> The visibility is defined by the following visibility levels:
> SNAPSHOT - returns the last written key by the transaction, in case one 
> exists, otherwise, returns the key from the transaction snapshot.
> SNAPSHOT_EXCLUDE_CURRENT - returns the last written key by the transaction 
> that was written before the last checkpoint, in case one exists, otherwise, 
> returns the key from the transaction snapshot.
> SNAPSHOT_ALL - returns all the versions written by the transaction including 
> the one in the transaction snapshot.
> This feature is needed for Phoenix both for upsert operations and for correct 
> rollback of the secondary index on transaction abort.
> Explanations for this feature can be seen in [TEPHRA-96]. 



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